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FAQs on Pond Water Chemistry, Physics

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by Robert (Bob) Fenner

High ph and pond algae
I am having trouble with a high ph and pond algae in my pond.
<Ah yes; very common in the warming months... esp. given filtration technology and maintain practices that allow/promote the accumulation of fertilizing/wastes (N, P, K)... the one drives the other. That is, higher pH is beneficial to noisome algae proliferation, and they in turn drive the pH UP!!!>
My pond is 758 gallons with a ph of 9.0 It was higher before I put in a little new water a week ago. It is better now, but still high. We have naturally hard desert water. The fish in my pond are pond goldfish. Being summer I am feeding the fish every day. We did a total pond cleaning and put in new water about 3 weeks ago. The water is now brown and cloudy again. Would a beneficial bacterial additive help?
<Mmm; am a (new) fan of the Nualgi product for ponds... I'd try this...
Otherwise shading, use of chemical filtrants to remove nutrient, water change-outs... Have you read on WWM re Pond Algae Control? Do so>
Would algaecide help?
<No to this; again READ>
Would a phosphate filter help?
<Yes; likely so>

Would feeding less often help?
<You are correct here... less volume/weight of food and better foods (like Hikari) are of use>
Should I muck out the whole pond again?
<Some weekly mucking in warm weather months is of use. Not too much though... Cleanliness is not sterility>
What can we do to fix the problem?
<Further reading on WWM>
Thank you.
<Welcome. Bob Fenner>
Re: High ph and pond algae       6/15/15

Thank you Bob! :)

Chemicals         5/16/15
I have a backyard pond and was told I could use A Concentrated Spa Shine Clarifier for my pond.
<... can you tell me what the ingredients are in this "floc?"
I have fish and don't want to use it unless I know it is safe for them.
<Stop. I would not use this product in a biological pond>

If it is safe, how much would be used per 100 gallons. Could you advise?
Thnx! Sami
<Bob Fenner>

Cloudy water    10/15/13
Yesterday I accidentally got some nontoxic liquid cement sealer in my pond water. The fish appear to be ok. But the water is very cloudy. I have already tried a water clarifier and my water is still cloudy. Should I perform a pond cleaning to change out the water in my pond?
Thank you.
<I'd change out a good deal/half of the water here... keep an eye on the livestock; make ready to move if necessary>

Thank you so much! I'll do what you recommend as soon as I can. Thank you.

pH in a Koi pond   6/22/10
Dear Bob
The water from my tap is 7.8 consistently. The water in my new (no fish yet) epoxy-painted Koi pond is 8.3 to 8.4
<Mmm, yes?>
I put 1 gallon of water in a bucket and tested it and it was 7.8 I left the bucket on my porch over night and the pH was 8.1
Does that sound strange?
<Not too so... the most common explanation/cause here is dissolved carbon dioxide being liberated when such water is exposed to the air>
I run all tests at 1pm daily, so there's no day/night differences in my testing.
I know that Koi can tolerate a lot of different pH levels ... but not drastic changes ... so my problem is that with every point my pond changes from that of my tap, the more lethal my tap water becomes in the event of a waterborne emergency.
<I see... would be a good idea if you could either store a good quantity of water, or barring this, had an emergency/contingency plan to process a largish volume... likely with an inorganic acid. This is DANGEROUS w/o a firm grasp on understanding alkalinity AND pH, pre-testing for same, and practicing batch processing of such volumes to assure that you don't drop the pH too much, too soon>
The only solution that comes to my mind is to make
enough of a water change every day that the water maintains a consistent relation to the tap, but that seems like giving up. Any words of wisdom?
<I have tried to say what I think I want to say before... one on one... Putting statements on the Net, in print is decidedly worrisome (to me)...
Might I ask you to read here:
and the linked FAQs file above... particularly re pH/Alk. Bob Fenner>

Cycling a new pond... Water treatment for chlorine/amine, and very high pH    5/26/10
Hello Bob.
I am currently cycling a new 1,200 gallon Koi pond and I have two concerns, one regarding additives and a second regarding Ph. If I add Amquel or De-Chlor to each batch of 120 gallons of water I change, won't I eventually end up with a pond filled with hydroxymethanesulfonate (Amquel) or Thiosulfate (De-Chlor)?
<Mmm, no... these molecules are transient... break down...>
I know that "better" is always a relative term, but in real world terms how much better is it to aerate the water for 7-8 days to dispel the Chloramines naturally versus dealing with them chemically?
<I wouldn't sweat adding any such DeChlor(am)inators if you're only changing this amount... ten, twenty percent of the volume period. I change out a good third of my fancy goldfish water w/o any such additions. The sanitizer is complexed "enough"...>
Regarding Ph, at 10 Am today,
<Yeeikes! You need to find out the source here, and correct it...>
I tested the pond which has been filled since Saturday and the Ph was 8.4. Our tap water tests at 7.8 and the 200 gallon tub that I have our brand new quarantined Koi in, filled for 8 days, is 7.3. Why would an empty pond, still containing chloramines, go up?
<Something alkaline there... Likely a cementaceous product... Is there new concrete, mortar in contact with the water? Was it acid-washed, otherwise sealed?>
Our local Koi store has the same municipal water supply and has told me, basically that "the Ph is the Ph.
<... Okay, "idiocy is idiocy", your turn>
If you are going to try to change and buffer every gallon of water that goes in, you will become a mad (angry)
chemist and the water will become chemical sludge, both in short order."
<... I agree with the sentiment here, but this pH is dangerously high...
Many important biochemical reactions will work against you unless you can discern and correct the source/s of this high alkalinity. This is extremely important... Your fish will suffer, indeed all livestock here... and you will have REAL algal troubles if you neglect this/these actually, aspects of water quality>
What should I worry about and what should I not?
<... do worry. And read:
and the linked files above... I've got to pen a piece on pH and alkalinity for Ponds...>
Thank you in advance,
<Welcome. Bob Fenner>
Re: Cycling a new pond, high pH anomaly
There was a VERY tiny bit of Portland cement used to fill a chip in the edge of the waterfall, maybe the size of a thumb.
And just to be clear ... the pH was 8.3 when tested at 10AM ... not a pH of 10.
<I see... well...>
I too am curious as to how a fill from city water @ 7.8 rises to 8.3 (which by the way it has stayed for 3 days now) and my plan is this.
<Could be aeration to an extent... algal growth as well; though it, the water, may not appear green at all...>
First I want to wait another 2 days and hopefully see no changes. Then use a buffer to get the pH down to around 7.8 THEN verify that it does not go up again.
<Mmm, there are a few approaches to this... my fave groups include biological mediation and shading... Live plants will/can do both>
If it doesn't go up, I had a one time incident. If it goes back up, I have an ongoing problem. Concur?
In a running pond & waterfall but with no fish, plants or biological cycle at all, would you expect the pH to remain, change slightly downward or change slightly upward?
<Mmm, barring any other outside influence, the pH should rise initially from aeration... the driving out of dissolved CO2 mostly, addition of higher concentrations of dissolved O2... then... IF there are algal proliferation issues, rise during the days (sometimes dangerously), dropping a bit (also trouble) at night... OR overtime w/ some alkaline
reserve, reductive biological influences will lower pH... w/ food, leaf,...waste accumulation>
Thanks again!
<Oh yes. B>

Sea shells in Koi Pond 5/10/10
Hi, folks... know I can always count on you for the answers that can't be found anywhere else!!!! Is it alright to put sea shells in a Koi pond?
<In general yes... some are too sharp, but chemically should be fine. Are almost all calcium carbonate... of benefit long-term in the reductive environments humans "keep">
These are shells collected from the Caymans and Australia that I have boiled on the stovetop, rinsed with tap water, drained and dried overnight... and are now soaking in an old aquarium outside in dechlorinated water.
I'd like to put them in two shallow ponds (5' x 8' x 2'd) that empty into the main pond. Of course, that's if you tell me that they will not cause any problems with my finny guys. They have just about reached their growth potential (except Shrimp... he's the one I wrote you about several years ago with the crooked tail... and he's almost 2-1/4' long now). I've been feeding nothing but sinking pellets and he has no problem eating now.
<Ah good>
So, I'd appreciate your thoughts about the shells. I have some really beautiful quartz along my stream beds that would complement the rich colors in the shells. Again... only if their presence won't hurt my fish.
Thanks again for your help.
Barbi Morell
<Welcome Barbi. Bob Fenner>
Re: Sea shells in Koi Pond 5/10/10

As always, thanks, Bob... and all the crew who have managed to keep me sane over the past 10 years. Barbi
<Me too Barbi... BobF, who has used such seashells in Koi/ponds for many years himself>

High pond ph and water source 7/29/09
Hello, crew!
I've received great information from you before regarding my pond, so here goes another question...
<Fire away.>
My pond ph starts out at 8.0 in the early morning and rises to 9.0 in the afternoon.
<I see; presumably a combination of photosynthesis, respiration, and changes in temperature. Broadly speaking, pH goes up during the day as plants absorb more CO2 than they release, while pH goes down at night because plants don't absorb any CO2 while still releasing CO2, and the fish release CO2 as well. CO2 makes water acidic, so when there's more CO2, which is what happens at night, pH drops, and when there's less CO2, pH rises, as you see during the day. This is absolutely normal. There's a really good publication from the Southern Regional Aquaculture Centre that you might want to read, here:
It covers the science as well as what you can do to manage this.>
Of course, ph rising is normal through daylight hours. I'd really like to lower my ph as it is keeping my marginal plants from absorbing nutrients, therefore, they are not growing and they look very sickly. However, my goldfish are fine.
<Changing pH is tricky, and by default, I'd recommend against it. It's much better to select plants that tolerate high pH levels, and work from there.
As you observe, Goldfish don't mind these daily pH changes at all.>
I am not comfortable using ph down, and I know both low ph and large ph swings can be lethal to goldfish. My problem is that my tap water source's ph is 8.0, so water changes won't work either. Any suggestions?
<Your tap water is presumably reasonably hard if you have a pH of 8.0. As you know, carbonate hardness inhibits pH drops, so one thing to do is check your carbonate hardness. If the carbonate hardness is low, say, much below 5 degrees KH, then adding the Rift Valley cichlid salt mix at half or full dose could be helpful. A recipe is here:
Alternatively, you could use products like Seachem Pond pH Buffer, though to be honest, I'm leery of such products unless absolutely necessary. I'd strongly recommend reviewing your marginal plants, and either choosing species better suited to alkaline soil, or else put them in (buried) planters that would keep them isolated from the pond water, if you really think this is what's stressing them. I'm not actually all that convinced, though acid-loving plants will, needless to say, not like pH levels as high as 9.>
Thanks very much,
<Cheers, Neale.>

clay pond, cloudiness  7/6/08 Hello, <Hi there Ter> I have a pond that is about one acre around and about 15 feet deep in the middle. The problem i am having is that it has a clay bottom. This makes the pond look cloudy. Is there anyway of getting the clay sediment to settle so that the water will look clear? Thank You <Yes... a few ways... some simpler, cheaper... longer lasting than others... There are flocculants that can/will precipitate out whatever it is... you can read a bit about different types in books, on the Net... many places use Alum (aluminum sulfate)... There are biological means... aeration... again, depending on your water quality, what the root cause/s are... Do you have water quality stat.s to provide? Bob Fenner> Re: clay pond... reading 07/07/08 Hello, I do not have any test results of my pond nor do i use any type of filtration. What happens is that in the spring when the spring runoff is happening the water is clear. But once the pond stops draining the water turns cloudy. I was hoping that there may be some way of using a natural chemical or maybe having some type of plant cover the bottom so that the clay is covered. Any suggestions would be very helpful. Thanks <... there are, as the saying goes, "all kinds"... What to use depends again on the physical make-up of the basin, the overburden/bottom, your budget, goals... Read here: http://wetwebmedia.com/PondSubWebIndex/Pond%20Sub%20Web.htm RMF>

Water in the pond... from a lake?  2/21/08 I've recently moved to NC and live on a lake. I want to put in a fish pond and since we're in a drought here, can I use the lake water to fill my pond? I will be "moving" my fish from SC to NC before the summer's heat. If I can't use all lake water could I use a 50/50 mix? Thanks for your help, Debbie <Mmm, there are issues with potentially importing the three P's... pests, parasites and pollution... Do you keep natives in this pond? If so, not likely much, as much an issue. Bob Fenner>

Water sealant for Koi pond waterfall   8/24/07 I have a Koi pond (see www.interall.co.il/pond.html <Nice pix and great documentation of your project! Glad I wasn't there digging when you hit those rocks!> for further details) and I would like to use a water sealant on the edging stones as well as the waterfall stones so as to inhibit Ph rise (Ph is at 8.4) as well as GH (16) and KH (10) rise. I have found Thompson's (r) Water Seal (r) Clear Multi-Surface Waterproofer http://www.thompsonswaterseal.com/products/list.asp?show=home.products.wtrPrf.multi and was wondering whether over time the sealant would leak into the pond. Thanks, Hank <Mmm... not much of an issue... as the material is quite chemically inert once it is cured... But... don't have much confidence that this application will last... or get you "where you want to go" here... How hard, alkaline is your source water? I might set up a trash can... near the pond... to adjust the water quality over time/changes... and use some live plant material as a mediating influence in the meanwhile... Not (too) hard to slowly drive, modify water chemistry over time here... Bob Fenner>

Pond water testing   7/15/07 Robert, <Craig> I'm writing to ask for some help reading my pond water test results. I've guide lines that came with the kit are so vague it has me confused as to what I need to be doing, if anything, to ensure the pond is in shape. I tested my water and have been trying to figure out the readings and was hoping someone could lend me a hand. The pond is 1.5 acre and 35' deep and the numbers are: PH 6.0, <A bit low> AM Nit. .3ppm, <Trouble, if so> Nitrite 0, ALK 168ppm, CO2 40ppm, <Spurious for sure> Hardness 44ppm. Thanks so much for helping me figure this out. Craig <Umm... I'd have someone come on out and look with other test gear... Maybe a member of an aquatic garden club... or a farm bureau rep.... You might have to pay for a lake management consultant to explain what is going on here... Do you have a destratifier/aerator at work here? I would... Have you read on WWM: http://wetwebmedia.com/PondSubWebIndex/Pond%20Sub%20Web.htm Too much to walk you through what these numbers might mean... but something/s not right... Including your kits I hope. Bob Fenner> Reusing Dried Rock...Not Always Good - 09/29/06 Hello, <<Howdy>> I was doing some research on live rock and could not come across anything on this. <<Okay>> I currently bought a saltwater aquarium from a friend who decided to quit the hobby.  I bought the aquarium about 3 or 4 months after he had drained his aquarium, and he left his 30 lbs. of live rock outside in the sun for that amount of time. <<"Live" no more...>> So I took it deciding I might could use it later to maybe seed it with fresh live rock. <<Will never be "the same" again>> Ok so here goes, is the live rock officially dead? <<...as the proverbial doornail>> I assumed it was so I placed it in a garden pond with goldfish outside of my house to let it just sit, but red algae is now starting to grow on the rock. <<Yikes!  Depending on the size of the pond, this rock can raise the pH well beyond what is comfortable/healthy for the goldfish.  At the very least, the (likely) low pH of the pond will have sapped much of the buffering capacity from this rock>> I was just wondering why this is happening, because I'm not expecting anything to happen, and this is freshwater. <<This has nothing to do with whether the water is "salted" or not.  You've seen algae grow on rock in fresh water haven't you?  Same thing happening here...though this rock likely had dead/dried organic matter deep inside that once the rock re-hydrated, is now contributing to a Cyanobacteria bloom on the surface of the rock.  Nothing strange going on here>> I was just going to use it in the new tank after a while to see if it could be seeded from other live rock. <<Could be used as "base" rock (after a few soakings/rinsings), but will never regain the biota it once had and may have little if any buffering capacity left.  Personally, I wouldn't use this rock to build a captive reef...maybe break up/use for frag bases>> Any information would be great, just wondering why its growing red algae.  Whats going on? <<As explained>> Thanks, Cody <<Regards, EricR>>

Pond, muddy waters   6/27/06 I have a natural pond approx. 800,000 gals that was dug approx 3 yrs. ago.  I have tried gypsum, and lime to try and settle the clay particles out of the water without much success. <Mmm, depends on what the charge, actual particles are made of whether such flocs would be of use> I am looking for something more permanent.  The particles are not from run-off or livestock.  If you have something I could try, please enlighten me on where to purchase it.  Thanks for your help, Jason Berry <... Need a bit more information. Have you had the water tested... pH, alkalinity, soluble phosphate, RedOx, dissolved oxygen profile. What sorts of life do you have here? Do you recirculate/destratify this water? Have a preference for biological controls? Let's chat. Bob Fenner>
Re: muddy waters  6/29/06
I have not had the water tested and I am not sure where to get it done. <Look on the Net, your "Yellow Pages" directories... government agencies ("Fish and Game") will know who is in this business in your area>   I have two aerators in it pulling water from approx 2' down spraying upward.   <Mmm, generally best to bring new water from near the bottom (though not the very bottom) of such basins... Yours has been treated, lined with what to make it water-impervious?> I have heard of trying some flocculent but I am not an expert and would rather know the cause of the problem first. <Alum (aluminum sulfate) is used in many places, occasions... with hard, alkaline waters... but I strongly encourage you to go a long, easy biological route to settle this...> The pond is kidney shaped and approx. 18' deep on one end.  I have approx. 200 catfish, 40 bass, and numerous bluegill.  I appreciate your response and look forward to talking with you again.  Thank You, Jason Berry <Much more to discuss. Have you read "standard works" in this field? Bob Fenner>

Pond pH & GH... RMF's regrettable advice... TAKE CARE!    3/29/06 Hi crew <Howdy> I am writing to you from Athens, Greece. I have 3750-gallon concrete pond (3 years old) with a self- built compartment filter and a massive UV to keep the water clear. For the moment the pond houses a group of wild caught fish (Common carp, Chondrostoma nasus and Leuciscus cephalus) and 6 goldfish. The pond is filled up with well water which is extremely hard pH > 8.5 and GH > 40. Although this is not the best option for the fish present, they have acclimated rather well since I never had any loss (not even during the 5 hour transport by car in mid-summer @ 40o C) <Have been to Athens... is very hot during the summer!> during this time and the fish are feeding well and have never been diseased. Anyway the next step is to breed these beauties, but as you might think they have never spawned with this alkalinity around. I was thinking of adding some peat in the filter, but I don't know if this is going to work in such a volume of water (besides the obvious drawbacks). <Yes... a mess> Do you have any suggestion of a cost efficient way to bring the alkalinity down? (Treated tap water, DI or R/O not an option for the time being). Thanks <The easiest and least-expensive is not the least dangerous. But I will mention it here... with tacit warnings. Use of an inorganic acid, like HCl... usually available as 3 molar Muriatic Acid... can be employed, OUTSIDE the system... as in batch-processed new water to be gradually placed in the main system with water changes... USE an alkalinity test kit, ascertain about the amount of acid to use per whatever volume water you are using/changing, mix and store for a day or more before applying. DO this carefully, taking pains to not spill the Muriatic on you, your clothes, to AVOID breathing the fumes, rinsing down the deck, plants that may have the acid spilled on them. Bob Fenner>
Re: Pond pH & GH - 03/29/06
Thanks for your immediate reply Bob. <Welcome> I agree with you that the addition of an inorganic acid is an option, not the best but I didn't leave you much slack... One last question though. As a marine biologist nothing would make me happier than tackling the alkalinity problem biologically if possible... <Can/could be done... there are plants in particular that absorb a good deal of alkaline earth material... Ceratophyllum, Myriophyllum species... Cattails/Tules, family Typhaceae mainly... even Nymphaeaceans...> Are you aware of a freshwater or an extremely euryhaline marine organism (possibly sessile invertebrate) that provided it is kept in "substantial numbers" takes up decent amounts of Ca salts? <Mmm, yes... there are some "pretty" rapidly biomineralizing invertebrates... but none that will likely make "much of a difference, timely..." Do you have another good-sized basin (hundreds of gallons) where you might culture some Thallophytes? Any local candidates that seem to become "scruffy" in the wild? Perhaps even recruited corallines could be put to use here. Bob Fenner> Thanks again.  
Re: Pond pH & GH  3/30/06
Once again thanks for the advice Bob. <Most welcome> I will look into the "plants scenario" a bit more thoroughly (sounds terrific) and will inform you about the outcome. The certain thing is that I have to extent the pond (special compartment of some sort) because plants and carp don't mix well... <Many possible experiments for you here... Exciting to consider and execute. Thank you for sharing. Bob Fenner>

Green pond water  9/13/05 Hi guys, <Ken> It is a long time since I last contacted you but then I received sound advice resulting in a positive result. Can this happen again? <I hope so> The water of my pond is now like pea-soup and I only see my fish on rare occasions. I have tried numerous commercial products that are supposed to clear the water but have had no success. I have also had a bale of barley straw of the recommended size for my pond, capacity 2500gals imp, in situ for 2 months and no improvement has been noted. The fish seem perfectly healthy and are eating well so there seems to be no problem in this respect. I have two pumps in operation, each turning over 2000 gals per hour, circulating the water through 2 biological filter systems, each of which is cleaned automatically each week and, although it is recommended that a dismantling and manual clean of the filters be done every 6 months I have, because of the state of the pond, been carrying this out on a monthly basis. This has not improved matters. The pond, because of its location, has been subject to a great deal of intense sunshine. I am talking of around 12 hours a day during the summer period. I realize that intense sunshine can exacerbate the algae condition and have toyed with the idea of putting a roof over the pond but do not want to resort to this until all other possibilities have been eliminated. What can you guys suggest? <... read here: http://www.wetwebmedia.com/PondSubWebIndex/pdalgcontrol.htm and the linked files above... there are a few approaches to consider... limiting nutrient, light, competitors, predators... lastly chemical controls... All will be revealed. Cheers, Bob Fenner>                                                                   In desperation and hope,                                                                           Ken Drewitt.

Well Water, sulfur, pond use 9/13/05 Hi Robert, <Susan> We have an outdoor goldfish pond.  We also have well water that has sulfur in it.  We killed our first batch of goldfish putting them directly into this well water and when we re-did our pond, we bought spring water to fill the pond. My question is this:  Can we let our well water sit for the sulfur to dissipate like you can do with chlorine in city water?  With our hot summer, we're going to go broke having to use spring water to keep replacing the water that's evaporating in the pool.  Thanks so much for your assistance. Susan <Very likely can use the sulfur-laden water... if only changing a bit... by trickling in replacement water, or to be much more sure, by storing, aerating/circulating new (well) water for a few days before mixing it in your pond. Bob Fenner>

Leaking pond - am I hurting my fish refilling so often? 8/28/05 Hi, <Hello there> We've cleaned out and restocked a pond in our new house. It's approx.  10feet by 5feet, and 3feet deep. It has a top level which waterfalls down to the larger lower level. We've put in a pump for the waterfall and a filter, loads of plants and have 2 happy little goldfish. Only problem is we have a slow leak in the liner somewhere as the outer  wall (stone and mortar) is constantly wet and we're losing 3 - 4 inches a week.   <Mmm... perhaps capillatory in nature... hard to fix...> We've tried emptying the pond and found a tiny hole, which we repaired with a   cycle repair kit on the advice of our local water centre. But either that didn't  work or there's more holes! <Or just a "damp" area twixt the liner and up...> Anyway, time is short at the mo due to work, so we've just been refilling  every few days and as there's no time to reline it this year, that's our only  option - but is it harming my fish????? <Mmm, not likely... in fact, replacing 3-4 inches per week of depth in a volume of this size is likely very helpful> Very quick 2nd question, sorry - one of my goldfish seems to chase the  other smaller one a lot. <Happens> At first I thought they were playing, but today I  noticed light patches on the rear sides of the one that's being chased, where  the nose of the chaser rubs his skin. Is this normal behaviour, are they  fighting, playing or even mating??? <Mostly the latter, the middle as practice... I would add a few more goldfish to diffuse the aggression here> Thanks, Allison Franklin (UK novice pond keeper) <Welcome, Bob Fenner, old-timer>

Green pond water 7/6/05 Hello, <Hi there> I've been running my pre-made 100 gallon plastic pond for 4 weeks now! I have 5 fishes so far and they look great. But know I have notice that my water has turned green! Is that normal? <Very common> Is there a cycling progress for pond water? <Yes indeed> It has been raining every day for 5 days. Could it be the rain water? <Mmm, possibly a factor> I have a pond master 1700 filter kit running my pond with a waterfall , and I would love to see my fish again what could I do? Sorry for so many ??? but I'm new to the pond seen. Thanks. <Read my friend: http://www.wetwebmedia.com/PondSubWebIndex/pdalgcontrol.htm and the files linked above. Bob Fenner>

Goldfish behaviour 7/4/05 Hi <Hello there> I have a very large garden pond - twenty foot by forty plus foot, four feet plus deep at one side, lots of goldish which do breed and so on.  However they do this every year and I now feel I need to know why. They are mostly just hanging suspended in the water, like they were asleep, although they did consent to eat a little yesterday and in the post dawn period they make little bubbles on the surface which linger most of the day. <Ah, yes> Can anyone tell me what they are doing and why?  No filter or oxygenator alas but I have lived here for more than ten years now and have managed so far okay. Thanks very much Angie Watts <They are experiencing changes in the pond due to the season... in essence being poisoned... changes in pH, mixing of bottom water... You might consider adding aeration, biological filtration... that will make this system overall more homeostatic throughout the year. Bob Fenner>

Vegetable Oil... In a Pond? Here's one for ya, <Ho boy> My step-son, in an attempt to prime a non-submersible pump went and poured a half of a bottle of vegetable oil in the hose per the manufacturer's instructions, <What the?> which is now in the pond. It's @ 500 gallon, 4" deep. I tried to skim off what I could with a pool skimmer net (which is now like paste) but it has coagulated into white clumps which is now on the bottom and covering the liner. Is there anyway short of draining and scrubbing with Dawn to get this out? Such as a natural biodegradable neutralizer or an  aggressively large cooking oil eating fish? James <Thank goodness you have a sense of humor. For this size system, I would drain all (including plumbing, filter...) and use a detergent as you mention. Do take a read through our Pond subweb re plumbing, check-valves... arrange for this conduit to stay primed when the pump is off, out... and no more vegetable oil! Bob Fenner>

Pond water quality Not sure whether the attached email got through originally.  I can't seem to find your response it in the FAQs on your website so I am resending. <Mmm, I don't recall seeing this message at all...> Thanks for any help you can provide, as I have never had fish before and don't want to do anything to inflict pain or suffering out of stupidity! Subject: Pond water quality                                                                         We are having difficulty getting pond water quality to an acceptable level for introduction of fish.  The pond is 1 month old and our pH tests 8.6 consistently. <Mmm, what is the pH of your source water? Did you "acid-wash" the basin/s down before filling? Of what construction are they?>   Our tester only goes to 8.6 so it might be even higher.   <This is too high... for your livestock and maintenance (algae control> We have tried pH down and large scale water change-outs and neither have budged the pH.  The water change-outs did help to bring the hardness (GH) down to 10, it was at 19. <Ah, good to see you have test capability for hardness... I would bet your alkaline reserve is still bolstering your pH here> Should we even be concerned with the pH or is 8.6 okay for goldfish? <You should be concerned. Much better for their health to be more near neutral (seven or so) and stable to a  point>   The guy that installed our pond said it was okay but I am concerned.  If the pH does need to come down what methods will work and work longer term? <Mmm, we need to start further back... see the first questions? If your pond is made of concrete, cement product/s, it may well be contributing all or a good part of the excess alkalinity here... in addition to your tapwater possibly.> On your website there was mention of non-chemical methods for tanks:  using peat moss in the filter and bogwood in the tank.  Would this also work in a pond that is ~600 gallon and if so how do you do this? <Could, but not recommended... other methods are better, easier, not so distracting in terms of water color change> The peat moss that I am familiar with is almost powder like. Our KH is at 16.  Should we be concerned with this? <Yes. The KH is too high as well... do you understand the relationships between these values, measures (pH, GH, KH)? You have one or more sources of "alkaline chemical species" contributing, making up your elevated pH as measured by the general and calcium hardness...>   If so, how do we manage the KH downward? <First and foremost, check your source water for these measures... if the pond water is appreciably different, some part of the construct is adding to them... and there are simple, straight-forward ways to change these adders to your situation. This is one of those situations where folks can work on the source/s or the effect/s... you want to focus on the former first. Then, if there is still a need/desire to modify your water chemistry, we can chat over means for doing so> Thank you for any help you can provide.  I have been searching for answers to these questions and seem to be finding lots of conflicting information. <Keep reading then... soon you will be able to sort out the fact from opinion and decide for yourself what to do. I suggest investigating basic pond water chemistry at this point. Bob Fenner>

B&B Bob, Whenever you get around to it, please let me know what kind of test we should have performed on our wells, I'll get some bids and start the testing. <Real good. Total dissolved solids, alkalinity, pH, nitrates, phosphates (total and soluble)> The house over there is incredible, I'm trying to talk my wife into heading over sometime, I appreciate the offer very much.  Mark <Hope you can make it. Bob F>

Goldfish are dying Hi.  You have sent my question back to me but did not reply with an answer. <I see....  My apologies, Todd; I have no idea what happened.  It looks like we had some cutting and pasting issues.> Can water kill goldfish but not guppies.   I did not see a answer.  Please respond with a answer as to the water. After 2 weeks with the new 12 goldfish, 9 out of 12 have survived so far. I am puzzled why 3 have died so far. The temperature is fine at 64 deg. Could there be something in the well water that kills goldfish and not guppies? <Okay, this was originally about a pond, right?  And your pond was only recently set up, right?  I'm sure it's not your source water, especially since your guppies are fine, but instead something happening to the water once it's in your pond.  When fish are added to a system, they immediately produce waste in that system, and without established bacteria to use that waste, the fish will be poisoned by ammonia or nitrite.  Please learn more about that (and more) here: http://www.wetwebmedia.com/PondSubWebIndex/h2ochempds.htm .  Please do get yourself test kits for ammonia, nitrite, nitrate, and pH, or at the least, take a sample of water directly out of your pond and bring it to your local fish store and ask them to test it.  They should be perfectly willing.  Okay so for a worst case scenario, let's say the water's fine, and something's wrong with the goldfish directly.  These are regular 'ol comets, right?  The ones usually sold as "feeders"?  These are often quite likely to be infested with some kind of illnesses, sad to say.  A good, reputable fish store (not a chain store, or store geared to all pets, but a store dedicated to fish) should be able to give you at least relatively healthy comets.  Do take a good look in their tanks, specifically the feeder tank where the fish you want are, and gauge the health of the fish.  Are they all huddled in a corner?  Are their fins clamped?  Are there dozens of dead fish?  Do they have little white sugar spots all over, or anything else amiss?  Stuff like that.  Since you don't mention any symptoms other than mass goldfish death, I'm really unable to suggest any illness.  I'm truly much more inclined to think that it's ammonia or nitrite buildup in the water.  Do get your water tested, and fix those values if necessary by removing/adding water, and certainly don't add any fish for now.  Do keep us updated, and take a look through other pond articles on WWM: http://www.wetwebmedia.com/PondSubWebIndex/Pond%20Sub%20Web.htm .  Good luck, Todd!  -Sabrina>

Pond pH & KH Hi <Anthony Calfo in your service> After testing my water quality after the winter chill I found that my pH is 9.0 and my KH is 53.7. Is this possible, or is my test kit wrong? <the pH of 9 is possible although unlikely. The KH is almost certainly a misreading short of you having a block of lime or new concrete in your pond <wink>. Is it possible that your test kits were allowed to freeze (kept in a cold garage, outside shed or the like)? Do retest with fresh test kits (perhaps your LFS will do it complimentary before you buy new)> I was under the impression that low KH would be a low pH.  <yes, often in concert> I know a low KH will cause a swing in pH so I need to correct this, <pH will go downward suddenly if low KH> I also need to lower my pH. My question is, if I add baking soda (and how much for a 1000 gal pond) will I be able to bring the pH down?  <wrong way good buddy... baking soda will drive it higher!!!> Last season I used Seachem's pond acid buffer which brought down the KH to let the pH stay down( last season had high KH and pH wouldn't stay down) If I use this product and baking soda I think I'll be fighting a useless battle.  <they work against each other...you don't need baking soda> any help would be extremely helpful. <once your tap water is in the pond it your pH and especially your KH should not be going higher unless something is leaching (rocks, runoff from rain, etc). Do examine the possible causes why. Anthony>

Salt in the pond? Hello Mr. Fenner, Thank you very much for the services you provide on your web site. I've enjoyed reading many of your articles on ponding, as well as marine aquariums and fish. <I hope as much as I've enjoyed building the site> I have a 35 gallon barrel pond in my back yard, with a fountain/filter set-up, and was wondering whether adding aquarium salt would be beneficial, as a regular supplement.  <Mmm, not as a "regular" addition... once placed, the salts don't leave except by water changes and splash... And many folks have enough salts in their source water already... by and large I wouldn't be adding salt for the sake of maintenance> I've heard this is good to do from my local fish store clerks/owners, but have seen dissenting opinions on the web, as well as different ratios of salt:water. 1 fairly standard ratio I've heard if 1 lb/100 gallons, however I do have plants (Anacharis) and want to keep them. My fish seem to be doing fine w/out any salt added, I'm just wondering if it is better to have a little added, then none. Thank you very much. Calvin <I would leave off with adding salt... but do regular water changes... during the warm months of the year. Bob Fenner>

Green Pond water (Tropical Sciences Labs, Phoenix) We have just gotten a 64oz bottle of Green Relief known as T>S>Pond by Tropical Science. Our pond is 22" deep x 5' x11'. We have treated it twice with 2/3 of a cup and our water has not improved at all. Could you please advise us as to the amount of this product to use to get our water back to a clear status?? <Hmm, this is a BIG question... having much to do with what your water chemistry is, livestock, filtration... I tried Tropical Science's website (.com) with no luck... here's their number in Arizona: 800-646-3611> We would greatly appreciate any help we could get. We tried to contact Them directly but they are not listed as I have been able to fined. <Please read over our sites pond sections (www.WetWebMedia.com and good luck. Bob Fenner> Thanking you George Black

Foam on pond My pond is beginning to get foam on the surface, I've read that this is from excess protein.  <Hmm, well sometimes from this... other times dust, leaves decomposing, food oils...> Could the foaming possibly be from the high amount of pollen going into the water? <Oh, yes> I've been netting out the big clumps but it can still be seen floating in the water, making it a brown tint. Thanks for any help. <I would do your regular maintenance, water changes for this time/season of the year, including water changing, vacuuming the bottom... and maybe overfilling the pond a bit to rinse off the pollen periodically... any chance of rigging a fine mesh intake trap/float to strain this out? Bob Fenner>

Koi (environmental disease) Hi I may be jumping the gun a little here, but last year I had a wipe out of a few Koi. The Koi are acting a little strongly. Scratching once in awhile (don't know how much scratching is really bad). They are a little skittish and I saw my smallest Koi hiding out a few times, which he never did before. There are no spots that I can see. Do you think I should use formalin or some other product or wait to see if it gets worse? <Maybe... Yes, I would use a bit of salt (water softener type)... a pound per hundred gallons... placed a third at a time, every two days... This will cure most any common complaint...> Ammonia 0, Nitrite 0, Nitrate 0, pH a little high 8.4 trying to get it down (problem is tap water is near 9.0) The pond is 1200gal and has an emperor aquatics UV sterilizer. Thanks <Would adjust the pH downward to about 7... with organic or not acids... this covered on our site (hopefully), www.WetWebMedia.com... or let's chat it over. Bob Fenner>
Re: Koi
A couple more questions: How long do I keep the extra salt in the pond? <For a couple of weeks beyond apparent (scratchy) troubles... then it can be slowly diluted out with water changes> and for lowering pH, is the pH down aquarium pHarm. makes suitable or is there a better way of doing it? <Think this is phosphoric acid (dilute), but at any length, yes, it's fine... but you will likely go broke going this route... Do get/use an alkalinity test kit... and learn to make these changes slowly (over days, weeks)...> On wetwebmedia.com it says soda ash stabilizes it, but does it lower it? <Yes... read through the pH, alkalinity and you section on the WWM site. Bob Fenner>  

Aquatic Gardens

Ponds, Streams, Waterfalls & Fountains:
Volume 1. Design & Construction
Volume 2. Maintenance, Stocking, Examples

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by Robert (Bob) Fenner
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