The Root of All Evil- Low Dissolved Oxygen 4/9/08
Guys, thanks for all of your help, my system was super saturated but I have definitely made headway. I think I finally bumped into my ultimate problem and need your guidance though, low dissolved oxygen!
<A not uncommon source of trouble in captive aquatics...>
Here's the setup, 900 gallon system. It consists of a display (160), a sump in the basement (150 gal), a refug with no sand and just Chaeto (50 gal), and two 300 gal tanks. The issue is, and I never realized this when doing so but because I have a little monster (4 year old),
<Ah, children... the promise of tomorrow>
I removed the sump to the display a few years ago and have had weird issues since! The sump in the basement pumps directly to the display, the display has 3 400w halides, closed hood with two fans. There is 50 feet of pipe between the basement sump and the display, I believe this to be causing low oxygen in my system. Further, the sump in the basement pumps to my 300 gallon tanks through another 50-60 ft of pipe. I have big-time flow, a clean system, killer skimmer, use ozone but I am never able to get ORP above 300-325,
<This... is high enough>
I easily supersaturated the carbonate, a sera O2 kit is giving me a reading of 4 ppm
<Low>
(I don't normally buy their tests but based on all of symptoms I can believe it). System ph wont go above 8.15
(I used to drip Kalk but in an attempt to maintain 8.3 I super saturated the water). If I take a cup of system water outside and aerate it, ph rises to 8.3.
<Not uncommon>
Skimmers are located with the sump (if I were to draw a pic for ya the sump would be located in the center of the system, with the tanks 40-50 ft away). Finally when I take filter socks off the system, polyp extension increases big-time!
<Need to clean/switch these more often... perhaps daily...>
I do aerate RO and water change water.
So here are my questions: I am reinstalling a sump under the display today and will be aerating it, the sump in the basement will feed the display, the display will feed the "mini" sump under the display, and a pump will return back to the display. The mini sump will also be plumbed into the return lines going back to the basement sump. I will also be doing something similar on 300 gallon tanks. Will this be enough?
<Mmm, maybe...>
Should I try to aerate the 50 ft drain lines themselves?
<No>
From reading Calfo's book, it sounds like oxygen drives ORP (obviously), ph, and buffering capability.
<All so to an extent>
The only other options here in my opinion would be to add smaller skimmers to each tank for maximum aeration, or to break the system into two separate systems and eliminate the 50 ft of pipe, I just had a preference one large system as it provides for greater stability (at least in theory!). Thanks for any advice, you guys kick butt!
<Mmm... well... a few things to state... First, I'd definitely be "checking the checker" here... Perhaps borrowing someone, or club's, or a store's DO meter... measuring dissolved oxygen a few times during the day, night... You may be a candidate for adding more circulation (some of those spiffy in-tank pumps that mount on the side...), perhaps the adding of a large amount of fine sand in that sand-less refugium (a bunch to speculate here)... Bob Fenner>

Gas exchange... wet/dry, skimmer, tight lid, and oxygen  12/23/07
Hello and thanks for all of your great info on this site!
<Hello Kevin.>
I have a 55g aquarium with 50 lbs of live rock, 30 pounds of live sand, one small clownfish, and about 25 snails (Astrea, Cerith, Nassarius). I'd like to add another clownfish and some other small fish (haven't decided what yet).
<Do research your selections first for compatibility with your current clown.>
I have the CPR dual BakPak hang-on-back skimmer with no bio-media in it.
There are two MaxiJet 1200's driving the skimmer and two additional MaxiJet 1200's for extra circulation.
I used to run an EHEIM wet/dry 2229 with some of their EHEIM Substrat bio-media. The nitrate levels were around 30ppm. After reading through the FAQs on this site, I decided that the liverock should be sufficient for bio-filtration and removed the wet/dry. I'm still slightly concerned about aeration/oxygenation without the wet/dry filter.
I have no airstones in the tank. I like to keep it clear of bubbles.
<Yes>
I think the skimmer should be more than sufficient for oxygenation, but I turn it off using a timer for about 6 hours a day since the aquarium is right next to my television and it's just way too loud.
<Really? Is it suction noise? There should be a little silencer on the end of your airline, these skimmers should not be that loud.>
I also think the other two MaxiJet 1200's, which are running 24/7 are probably moving the water around enough to get some oxygenation at the surface. However, I have the top of the aquarium almost completely sealed with acrylic to prevent SG changes, evaporation, fish jumping out, etc...
Is the six hour daily time period with no skimming enough to significantly decrease the oxygen level in the tank?
<With the top sealed up and an increasing fish load, yes.>
How much of the tank lid needs to be "open" in order to allow for air exchange? Would a couple 1/8 or 1/4" holes be sufficient?
<Not really, go larger, more open. >
Is there some way I can use the wet/dry for the sole purpose of increasing oxygen without increasing the nitrate levels? Would running it empty do the trick or do you really need all of the surface area for promoting oxygenation?
<This is a great solution for you; it will still provide gas exchange. I also recommend investigating why your skimmer is so noisy. You should not have to turn it off at all.>
Thanks, and have a great holiday. Kevin
<Welcome, happy holidays to you also, Scott V.>

- CO2 Injection for a Reef Tank -
Good day. <Good morning.>
I have been admiring your website for quite some time and I now may have a question worthy of asking you. I noticed that the area of FAQ's under dissolved oxygen  ( http://www.wetwebmedia.com/dissolvedoxygen.htm ) is empty so you may want to put this in there as it may apply. <Ok.>
My question relates to adding C02 to my reef tank. <Why would you do such a thing?>
If I bubble in C02 into the tank will the skimmer take it out by trying to saturate the water with another gas ( air / nitrogen and O2 )? <To a certain extent, but depending on the efficiency of the skimmer it likely won't get 100% of it.>
I have a 110 gallon tall tank with an 80 gallon sump that has been divided for filtration and for macro algae growth to remove dissolved organics. I would like to inject C02 into the water to help with the macro algae growth (razor Caulerpa) I understand this will effect my PH so I would have to watch this closely. <I wouldn't recommend this. Should be sufficient CO2 from other organisms in the tank and also from the plants and corals during the dark phase. The presence of CO2 is rarely the limiting factor in algae growth but rather the other foods: phosphate, nitrogen, and potassium... [think fertilizer] which typically come from the tanks inhabitants.> I am currently looking into getting my calcium reactor going thus I may have some residual C02 in the effluent... <Usually not much... the residual amounts are typically used up very quickly by other processes, including your algae and also skimming, overflows, etc.> That may be enough to help the plants enclosed are some pics of my set-up ... I have been doing this " reef thing " for a good 10 years or so and there is still so much to learn, any comments will be appreciated. <I think the reason for slow algae growth is a lack of organics... you don't have much in your tank, and it's my guess that as a result you're not feeding much. I will reiterate, I don't think it is wise to add raw CO2 to your tank... the water will acidify and cause other problems - deplete your buffers, etc. Much better to add CO2 via a calcium reactor, where the 'reactor' will use most of the CO2. As for you the growth of your algae, I'd look to extended lighting and dissolved organics from fish/feeding to fill this gap. Give the system some time and I'm willing to guarantee that the algae will take care of itself, to the point that you'll be asking us how to get rid of it.>
In the sump pic you will see a top fathom skimmer, this has recently been replaced with a modified version of the TF utilizing a air injection system before the impeller and a taller reaction tower. This modified skimmer pulls out some nice dry foam on a regular basis. The lighting on the sump is not shown either as this sump pic is an early one. I am running close to 100 watts of compact fluorescent light on the "refugium".
I hope this question is worthy of your attention.
Kevin
<Cheers, J -- >

Dissolved Oxygen Issues?  Overheated Tank
Hello crew,
Ill get down to it, I know you have a ton of mail to answer.
<Hello, Ryan Bowen helping today>
My corals look ill. Withered and not opening. Problem is, I have never had a cleaner tank. <Clean...what a variable word!> 75 gallon with custom sump and refugium. Lighting is 2 x 175 watt MH with 2 x 48 inch actinics. Tank has been up for 7 months, and corals have been in for 3 months. 3 weeks ago, they began to look sickly. I change 5 gallons of water every Sunday and the make up water is with RO/DI. <Do you dechlorinate?> I have kept tanks for 10 years, but I have a whole new setup this time, (new house) and I have never had MH lightning before.  The tank did reach levels of 86
degrees when it got hot here, but I have managed to control it with a fan and have purchased a chiller. The temperatures here have toned down a bit
and the tank has been a comfortable 76 to 79 for 2 weeks. No change in the appearance of the corals. <Well, temperature shock can easily kill the symbiotic algae living in the tissues of your corals.  A few week's recovery is on order.>
The only other issue I can find is that my salinity was a bit high due to evaporation, but I have corrected that and still no change.<Salinity has a direct relationship with heat, so the heat shock is accompanied by salinity issues as well.> I have even changed the amount of time the lights were on, from 9 to 10 hours to 6 hours during this time to see if that was the issue. <Leave it alone, your corals will respond better to predictable lighting times.> I also changed the 900 gallon per hour power heads in the tank to Visi jets 900's. much lower flow.
My green star polyps and blue mushrooms look great, and all fish and shrimp look fine in the tank. Fish consist of a yellow tang, 1 perc, and a couple
of green dichromis. (didn't want to have a stocking issue). What am I missing? <Skimmer?  Calcium and alkalinity?  Dissolved oxygen levels too low?  What's your pH?  I need more to work with, sorry>
I would appreciate some advice, I can't seem to locate anything else that I should be checking. I even broke down and re-read Sprung's bible to see if I
could glean anything that I could have overlooked.
<I'd test dissolved oxygen, it sounds like you're overheating because the surface of the water isn't turning over fast enough, keeping oxygen high and heat low.  Read, test, re-write me! :http://www.wetwebmedia.com/dissolvedoxygen.htm>
Let me know if you can.
Quinn.

- Adding Pure Oxygen -
Hello again there fellers, all of your help has been truly welcome.  I have a question concerning the addition of oxygen to my tank by way of bubble counter into my skimmer to combat the CO2 build up that has been accumulating in my house since it is cold out and I have to keep my house closed.  My pH drops when I have my house closed because of the build up of CO2 and have tested for this specifically in the past.  Don't have the issue in the summer because my windows are usually open a lot.  Would it be unwise to add oxygen to my tank via a bubble counter hooked up to my skimmer for the added oxygen? <Hmm... I'd say adding pure oxygen could cause some problems - oxygen toxicity being my primary concern but also excess oxygen outside of the system. Chances are pretty good that any oxygen you add will bubble to the top of the tank without reacting with anything and instead going into the atmosphere. You're better off just using a bubble wand and an air pump and relying on regular air. The bubble action should help drive off some of the excess CO2. You might also want to develop an algae-based refugium under 24 hour lighting where you would have willing consumers of CO2.> Maybe one bubble per 5 or 10 seconds or more or less?  What would be the negatives if any? <Increased ability to combust and/or oxidize items in your home. But more so, that while good-intentioned, this will not produce the affect you desire.> Would this not increase the oxygen and counter the CO2 build up? <Sounds good in some ways, but the air we breathe is not pure oxygen - it's about 21% oxygen. Adding pure O2 is asking for trouble. Likewise, O2 is chemically very stable, so it's not very likely that it would react with anything in the tank, meaning you would still have roughly the same amount of CO2 in your system.> I have access to an Oxygen tank and would need to buy a solenoid and bubble counter.  I have quite enough water flow in my tank and am using a Euro Reef CS6-1.  It's a 180 gallon.  It pulls out massive amounts of gunk and have to clean it at least 1-2 times per week.  I have a lot of SPS along with a few LPS and softies.  Yes, I agree big load but am concerned with keeping the pH up.  I add Kalk daily at night which boosts the pH up from 8.06 to 8.3 at the most.  Also have a calcium reactor that does quite well at keeping the calcium and alk in tune.  Any thoughts on the cautious addition of oxygen? <You got 'em.> Thanks again, Jeff
<Cheers, J -- >

-O2 addition to combat CO2 buildup-
Hello, I have been e-mailing the below question to you for the past 3-4 days with no reply from you fine folks.  I searched your web site but didn't see the answer to the question I sent.  Please try to respond sometime soon. <I apologize for the delay, but unfortunately we don't have unlimited time and must answer emergency type questions first.> You are probably swamped with questions and haven't had a chance yet to get to it.  Thanks again, Jeff
Hello again there fellers,<Yo! Kevin here> all of your help has been truly welcome.  I have a question concerning the addition of oxygen to my 180 gallon tank by way of bubble counter into my skimmer to combat the CO2 build up that has been accumulating in my house since it is cold out and I have to keep my house closed.  My pH drops when I have my house closed because of the build up of CO2 and have tested for this specifically in the past.  Don't have the issue in the summer because my windows are usually open a lot.  Would it be unwise to add oxygen to my tank via a bubble counter hooked up to my skimmer for the added oxygen? <Unless you have horrible gas exchange, there should be no need for oxygen additions. It is important to note up front that the concentration of O2 in the water does not effect the CO2 levels.> Maybe one bubble per 5 or 10 seconds or more or less?  What would be the negatives if any? <I cant see any, besides it being a fire hazard.> Would this not increase the oxygen and counter the CO2 build up? <Nope> I have access to an Oxygen tank and would need to buy a solenoid and bubble counter.  I have quite enough water flow in my tank and am using a Euro Reef CS6-1. I had a CPR SR9 but was not too impressed with the amount of dissolved organics that it was pulling out.  Bought the Euro Reef for an incredible discount from a friend who bought it brand new but never used it. <Sweet!> It pulls out massive amounts of gunk and I have to clean it at least 1-2 times per week.  I have a lot of SPS along with a few LPS and softies.  Yes, I agree, big load but am concerned with keeping the pH up.  I add Kalk daily at night which boosts the pH up from 8.06 to 8.3 at the most.  Also I have a calcium reactor that does quite well at keeping the calcium and alk in tune.  Any thoughts on the cautious addition of oxygen? <How about either installing a second chamber on your calcium reactor to hopefully absorb any excess co2 or somehow connecting the drip line from your reactor to the mixing portion of your skimmer (AquaC does this on it's larger EV models) to blow off excess co2.> Also, do you recommend the use of Red Sea salt?  I can get a 200 gallon bucket on sale for $31.99 which is cheaper than the same 200 gallon bucket of Instant Ocean that I always use.  Not sure if I should take the risk or just stick with what's been working for me for the past few years. <Well, if it ain't broke, don't fix it I suppose. I'm not a big fan of red sea salt, but have since forgotten why (haha, I know, I know!). Sorry, it's late! -Kevin> Thanks again, Jeff

Oxygen Saturation Question - Emergency Plans
>Hi Crew:
>>Hi Gregory.  Marina today.
>Really quick question for you...not sure about the answer though.  All the power problems and storms on the East Coast recently have made me think of emergency planning.  (Just because I'm paranoid does not mean that there is not an international conspiracy to kill my fish!!)  Do you know (or can you point me to a book/article discussing) the approximate time that it would take a given amount of fish to lower the oxygen saturation in a tank to fatal levels?  I know this is impossibly complicated but I'm just looking for some sort of ballpark range (hours/days??).  If it helps to be specific, I have a 110g with three 4/5-inch tangs, two 4-inch butterflies and a centropyge angel.  I assume that they could last quite a while in this tank, but I may be wrong.
>>Indeed, just saw a query from someone who lost his fish by the end of the day (8-12 hours, if I recollect correctly) due to pump failure.  Different catastrophe, same result.  Good idea to plan.
>I read through the fax about oxygen, but didn't find anything discussing this sort of timeframe.  As always, thanks for your time and experience.  BTW, I'm really enjoying the little messages about NMA V2.  Must be alternately exciting and wearying to be working on such a project.  Take care, Gregory Fickling  
>>Absolutely, I'm hoping my contributions to the previous tome were well received and might be taken advantage of again.  ;)  I suggest you go to a bait shop and buy several battery operated air pumps.  These tend to be both cheaper and more powerful than those you might find at your LFS.  Unless, of course, you can afford to and have a place for a generator.  Marina

Science Project Help
Dear Crew:
My daughter is doing a science project attempting to prove that a plant adds oxygen to its environment using gold fish and their environments. My husband wrote to you when we began this requesting information on testing the O2 levels in the water.  We were unable to find the test kit you recommended and none of our pet stores could order it.
<Try the etailers... listed on our links pages on WetWebMedia.com>
Is there another way to tell through the behavior of the fish?  Is it possible there is a good website out there regarding goldfish behavior in relation to the oxygen level in their bowls?
<Would have to search... the same as you or your daughter>
This thing is due Tuesday and we are about to pull our hair out.  Everything we have found has been on pond gold fish or behavior when chemicals were used in the fishes environment.
We have tested nitrites, ammonia and ph levels daily for this experiment.  Is there some way to prove a correlation between our results for those levels and the amount of O2 in the bowls?
<If you can rule out other factors... Bob Fenner>
Thank you for your help.
Cheryl Conrad

- Oxygen Testing -
Crew,
<Good morning, JasonC here...>
My 3rd grade daughter is performing a science project involving oxygen replenishment in fish tanks. She has set up 3 2.5 gallon bowls with goldfish. One is fed from a whisper pump, one has an Amazon Sword plant, and the third has no outside oxygen source. My question is where to direct her to find testing procedures to validate her research. She is from a gifted cluster class and has a very good grip on science. Can you recommend an avenue to explore please. <Sure... there are test kits for dissolved oxygen available, although they may not be in stock in your local fish store, they can be ordered there or online. The Salifert kit will probably be the most economic.>
Thank you for your consideration.
Steve Conrad
(Science assistant dad)
<Cheers, J -- >

- Dissolved Oxygen Problems? -
I need some major assistance on getting more dissolved oxygen in to my reef. <Oh?> I have had problems with fish lately.  They showed signs of oxygen depletion before dying suddenly. <Could be signs of something else...> There are droves of xenia, sps, clams, lps, and polyps that are doing great and multiplying. <So... they need oxygen too...> I suspected oxygen issues so got a Salifert O2 test and it read at 5 and needs to be 9 or higher. <That might be more an issue of waiting another minute to do the test - natural sea water is about seven PPM... so you're not really that far off.>
Let me tell a little about the system.  It is a 75 gallon Berlin.  The is 90 lbs of premium liverock, 2 175 watt halides, 2 100 VHO actinic, an ETSS 600 skimmer, with 2 genX pumps.  The tank circulates around a 1500 gallons an hour and 500-600 through the skimmer. <Yeah... with a skimmer, it's REALLY hard to have problems with dissolved oxygen.> The skimmer has been tweaked and runs great.  There is a powerhead on the left side of the tank pushing against the return.  There are 2 returns and they are near the surface.  The surface of the water has major agitation.  There is a 36 watt UV in the sump (sump has liverock only) (Could the UV be breaking down the O2?) <Not a possibility.> There are many types of macro-algaes growing in the tank. (Co2 build up at night?) <I really doubt it - it would be hard to get into that much trouble, but this you can test by cutting back some of the algae.>  
I need major help.  Ideas of equipment and such.  I thought the big skimmer would do fine.  I have tested the O2 many times during the day and it remains the same.  There is a lot of coral and two fish, but not too much.  I cut back the xenia and Sargassum majorly.   I had Chevron, Asfur, Sunburst, and pygmy fireball, but they all died in 4 days when I added the last two. <Did you quarantine the fish before you added them? Could be you introduced some Amyloodinium...> Then after a long wait I added 3 yellow tangs and the same happened. <All at once? My friend, I think your problem are more in your methods for introducing livestock than with dissolved oxygen.> The water is crystal clear and all chemistry is in line.   
I also have a 1/4 hp chiller that sticks the tank at 76 degrees.
Please shed any light you can on the situation; my hobby of 20 years is becoming a nightmare quickly as my fellow hobbyist friends give me major grief. <Look deeper... the answer is there somewhere, but I still think that dissolved oxygen is a bit of a red herring.>
Thanks for all your advice on the web,
Lee Larson
<Cheers, J -- >

Re: Reference to dissolve O2
Hi Bob I did not spell check my E-mail before I sent it.  In the message )2 is supposed to be O2 (oxygen).  Sorry I got trigger happy.
Thanks,
Lee Larson
<No worries. Cheers, J -- >

- Testing for Oxygen -
Hello again crew <And hello to you.>
I have yet another question about my tank. How can you measure the oxygen in your tank, is there a special tool like the hydrometer or something or can you just tell by all the bubbles floating around in the water? <There are test kits for this, although they are rarely seen - they can be ordered.>
Thanks again.
<Cheers, J -- >

Dissolved Oxygen/ GBD
>Gentlemen,
>>And ladies, thank you.  ;)
>>O.K., I've read every post about gas bubble disease and dissolved oxygen yet I still need help :)
>>As I understand it, it's not necessarily dissolved O2, but any supersaturation of dissolved gases (say, 110%-140%) held within the water.  That is to say, when you see actual bubble formation, the gas is coming out of solution into the water column, and not into the fish.
>Now, a certain amount of dissolved oxygen is good but too much could lead to gas bubble disease right?
>>Technically, correct.  Remember, this is not peculiar to dissolved O2.
>I have a Mag 7 as my return pump from my sump to the main, and it was spitting out a lot of tiny bubbles into my tank. After further reading, I realized that too many tiny bubbles was bad, so I sealed the leak that was causing it (check valve). Now I still have a small amount of tiny bubbles from the return line but there is no air leak to be found. Is this small amount acceptable?
>>That can best be answered by your fish.  If you're really worried about it, then breaking the water flow up (any type of "waterfall" effect, for instance) should cause all supersaturated gases to come *out* of solution.  So, you could, for instance, have the return line set just at the water's surface, but angled up so as to force a bit of a waterfall (but without causing splashing, which leads to salt creep).
>I read that sometimes air can be introduces into a pumps impeller housing which would be dangerous. I did let my Mag 7 run "semi-dry" for about 1/2 a second when I was first trying to get the plumbing right. Could this be the cause?
>>No, some sort of cavitation (as seen with boat propellers) would be more likely.  Once you've got any air pockets worked out initially, you should be golden.
>I've also noticed that my Magnum HOT filter spews out a bunch of air bubbles in short intervals once in a while. Is this something I should be concerned with?
>>My guess would be cavitation, again.  As I mentioned earlier, if you are getting actual bubble formation it means that whatever gases that are being held in solution are coming *out* of solution.  Again, if you're concerned about it, find a way to diffuse the water flow and break up its contact area (=surface area) interface with the air.
>How mush dissolved oxygen is ok/ needed?
>>Aaaahh.. now we're getting back into that chemistry my son has been throwing at me!  I really wouldn't worry about the situation unless you're seeing fish demonstrating symptoms of Gas Bubble Disease.  Do a Google search (I've also just learned of http://www.googlism.com --haven't used it yet, but what the hay) and you'll get *many* hits.  Here's a really useful one I just found--> http://www.reefs.org/library/article/cripes_kowalski_phipps.html
>Much thanks, Greg
>>Quite welcome, Marina.

Re: Dissolved Oxygen
Good Afternoon.
<J.T.>
    I have had a problem (since I started my aquarium in August of this year) getting an acceptable level of dissolved oxygen. It has typically been in the 4 mg/L range. All other parameters are perfect. I run my tank at 77 degrees F. and at a specific gravity of 1.024. We left the tank unattended this past holiday weekend (Thanksgiving). Since it was an extended week-end combined with the  fact that I have removed the lid from the tank, have a tank turnover of approx. 25 times per hour and I have arranged my pump returns to achieve turbidity at the surface, I experienced a high degree of evaporation. With the lowered water level, one of my pump returns was causing so much turbulence at the surface as to almost splash water out of the tank. I figured that this would have helped to raise the dissolved oxygen level. I checked my parameters and all is well (s.g. was in-between 1.024 & 1.025 due to the evaporation) but dissolved oxygen was only at 5 mg/L.  
    I know one of my problems is due to my tank design. I have a 45 gallon tall (12"D x 36"L x 24"T) which only gives me 2 square feet of surface area. I have been assured that my skimmer is properly sized (a CPR Bak-Pak 2R). After extensive reading at the Wet Web Media site, among others, I have to assume that my skimmer isn't working properly. I am only getting approx. 2-4 ounces per day our of my skimmer trap.
<This may be... all there is>
The water is a green/dark green in color with the "foul" odor everyone speaks of. Everything I read makes me believe the skimmate should be a coffee color and I should be producing more.
<You might be able to adjust the amount, fineness of the bubbles... raise the contact water level... in an effort to collect more, different make-up skimmate>
As a matter of fact, when I returned home from the long week-end (4 days) I only had approximately 4-6 ounces in the collection cup. I have adjusted the cup up and down attempting to get a better skim and am what I feel is the best point. I have the venturi air valve (attached to the Rio 600 power head) wide open to produce the highest amount of bubbles. I've actually removed the plastic valve screw allowing the venturi to run wide open.
    My bio load is fairly light. I have a medium Yellow Tang, small Flame Angel, medium squamosa clam, medium frogspawn, medium leather umbrella coral, small xenia (pom pom) and the clean-up critters (scarlet reef hermits, Cerith snails, Mithrax crab, cleaner shrimp, banded leg crabs, queen conch, abalone, serpent star, brittle star & Margarite snails)
Any other suggestions how I might be able to get my oxygen level up?
<It might actually be nearer to saturation (about 7 ppm) with the difference lying in the test device... But, perhaps adding a mechanical aerator near the bottom (an airstone) at one end of the system, will help to turnover your water more completely, rendering more of the unsaturated water at the air-water interface. Bob Fenner>
Thanks for all of the help.  J.T. Craddock

Re: pH alk?
Anthony, you are the man. 
<immodest or not...its sure nice to hear it :) Thank you my friend>
check this out. My pH was 7.93 when I put my probe in my tank. I then opened a window and within 2 hours the pH was 8.16. 
<yep...amazing isn't it. An interesting dynamic of modern housing (and better insulation) on aquaria>
the lights had been on for 4 hours, so I wasn't sure it was the normal pH increase. the lights are scheduled to be on for another 8 hours which would mean the pH should keep going up if it was a normal daily fluctuation. to make sure your theory was right, I closed the window and watched the pH drop .06 within an hour. Pretty weird, huh?
<amazing...yes. And it dropped at a time when it should have been going up confirming our suspicion>
my apt is 950 sq ft. and air tight. now I'm gonna do a big water change and try to figure out how to crack a window and not go broke running a/c full bore. thanks again, Neil
<best regards, Anthony Calfo>

The Conscientious Marine Aquarist (trigger feeding, high DO)
I love the book and am learning tons, Thanks.
A couple of questions.
1. I have a 48 gal. tank w/ one damsel, four clowns and a Niger Trigger (much larger than the clowns and damsel but all living peacefully together) and I feel the trigger wasn't getting proper nutrition from basic flake and frozen Emerald Entree so I bought regular store bought shrimp - is this ok to feed the trigger?
<Yes>
2. Is there a possibility for too much oxygen in the tank?
<In some unusual circumstances, yes.>
Thanks, Jake-Dallas
<You are welcome. -Steven Pro>

Dissolved Oxygen
Working on raising my dissolved oxygen in my 30 gallon q-tank. Anyhow, it has a MJ1200 powerhead, a AquaClear Powerfilter, and a remora pro (mag 3) skimmer on it. I just put a moray in there for quarantine for three weeks, but it looks like its gulping for air a bit. It's a slow gulp, so not like its gasping. Did a dissolved oxygen check and it shows about 4ppm, so I wanted to raise it. 
<yes... rather low indeed. Nice to be 6ppm or higher>
Anyhow, I don't use the MJ1200 aeration tubes (usually the skimmer on my larger tanks handles the oxygen for the tank). Anyhow, do the aeration on powerheads (bubbles) actually help dissolved oxygen, or it just bubbles and its marginal improvement ? 
<yes. helpful>
Wouldn't that cause the tiny bubbles that bad for fish ? 
<unlikely to become supersaturated>
Whets the best way to increase the oxygen in the water for inhabitants ?
<ozone on a QT tank is ideal with a controller. O2, Redox increase, disease control, water clarity, etc>
Thanks Ed
<always welcome, Anthony>

Re: Dissolved Oxygen
Anthony, follow up on this. Before I receive the ozonizer, what would be the best way to raise DO from 5ppm ? 
<water circulation that brings water from bottom of tank to the top>
I have a small power filter in there (tiny Duetto) which acts like a PH at 100gph. 
<rather weak water flow>
It has an air adjustment as well. When you turn the air knob, it outputs fine bubbles, at wide open, its almost frothy. Also a MaxiJet 1200, with airline hose. That obviously outputs larger bubbles. I have the Duetto pumping water above the water line (more surface agitation), and the 1200 just underneath the waterline with air bubbles.
<bubbles are not as effective at oxygenation as a fast turnover of tank water from circulation (top to bottom)>
So, are smaller bubbles better (frothy) from the duetto better, or larger bubbles from the MaxiJet better ? 
<neither...above>
Or should I just keep the Duetto return above the water, but not frothy. I have tiny bubbles everywhere in my tank right now trying to increase the DO, as you indicated that it won't be supersaturated. Makes for a bit cloudy tank though :-).
<bubbles are also quite irritating to some fish and coral... just improve or redirect water circulation in tank... bubbles if the fish don't seem to mind them>
Thanks, and have a good weekend. Ed
<thanks kindly, Anthony>