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FAQs About Water Evaporation, Make-Up H20: Rationale/Use

Related Articles: Marine Water Change, Captive Seawater Quality, General  Marine Maintenance

Related FAQs: Make-up Water 1, Water Changes for Marine Systems 1, Make-up Water: Gear, Frequency/Amount, Techniques, Water Quality/Adjusting, Trouble/shooting, & Top-Off System s, Controllers, Treating Tapwater Marine Water QualityMarine Plumbing


Big Change: Water Evaporation   6/24/07 Hello WWM, <Hello, GrahamT here tonight!> You are a tremendous resource and we can't thank you enough for the time and effort your whole team puts in to making this wonderful hobby even more enjoyable. The daily questions are a daily read for us - more so than the newspaper. Thank you again. <Thank you for your kind words on behalf of our dedicated crew! I am convinced that reading the dailies... well, daily, can make an advanced hobbyist out of any of us!.> We have a 75 gallon FOWLR which has been running nicely for three years now. As per your recommendation, we upgraded to a Remora Pro skimmer about six weeks ago. This has been maybe the best thing we have ever done for our tank. Producing an incredible amount of the nasty green stuff. <Very good to hear. Some people can fine tune the amount of food they give by the amount of gunk collected in their skimmers.> When we first introduced the skimmer, we had a difficult time keeping the temperature steady as the Mag 3 pump gave us 4-5 degree fluctuation daily. It was easily fixed by adding a small fan blowing across the top of the tank. <Ahh, yes... evaporative cooling can be very useful and economical.> Our tank temperature is now consistent at 76 degrees. The problem we are having is with water evaporation. <Hence the term, "Evaporative cooling".> Before adding the skimmer, we would have to add a couple gallons every couple days or so. Now we have to add three to four gallons per day. <Happens, I'm afraid...> There are no leaks anywhere and we are wondering why this is the case. At first we though maybe it was due to summertime, but we haven't had this issue in the past. <You're experiencing one of the drawbacks to evaporative cooling. Really, there isn't much to say here, since slowing down the evaporation means warming the tank. You should be ok with letting the temps rise slowly to 78-degrees, if you have a lower speed for the fan you use. Other than that, I think you're stuck with it. One thing you need to watch out for with increased water-loss through evaporation is the problem of concentrated "leave-behinds" that are being reintroduced every time you top-off, and as the water leaves, the levels are rising. If you use purified water and perform frequent water changes, this may not be a concern. Food for thought...> Thanks in advance for your help, Tracy and Scott <You are most welcome, folks! -GrahamT>

Freshwater or Saltwater To Replace Water Lost To My Skimmer? - 06/05/07 Should I use RO/DI or seawater for the replacement of the waste water created by my skimmer on my 65g? Skimmer kicks out about a quart of waste every day or two. <<You pose a very good question. One of the fundamental keys to success in the hobby is the ability to provide "stability" to your system. Many authors have/will state that water parameters such as salinity and temperature often don't have to be "spot on" as long as they are stable...though small gradual changes are usually deemed acceptable. But if I may digress a moment...I have been shore-diving off the coast of the Big Island of Hawaii where great quantities of cold, fresh, water were seeping out of the rock in to the ocean. This created stratifications in the water column where the differences in both salinity and temperature were neither small nor gradual...and the fishes appeared little bothered when traversing through one to the other. This doesn't mean I advocate we as hobbyists should be making/allowing large swings in our tank's water parameters...but it is some food for thought. But more to the point of your question...You "can" monitor salinity on a daily basis and make adjustments using a brine solution if you wish to do so, and in some extreme cases this may even be necessary...but for the majority of aquarists, as long as you are monitoring the salinity of your system and making needed adjustments during your water changes, topping off with RO/DI water (preferably buffered) to replace both evaporation and the gradual amounts lost to skimming is perfectly acceptable...in my opinion>> Many thanks in advance. Gene <<Is my pleasure to share. EricR>>

Evaporation Rock  3/22/06 Hello, You all are the best! <Hello! We aim to please> I have a 60g cube FOWLR and I recently added a 1/5hp chiller which successfully brought the temp and the evaporation down. Evaporation was one gallon a day and is now down to half that. <That is a decent reduction, I wish I had that.> I want it even less. I do have live rock sticking out of the water right under the halide. Do you think this is working like a wick and accelerating the evaporation? <It could be, but I don't think so.   However I would make every attempt either to control that evaporation anyway (How about an auto-drip?) but either way you should try to move that rock so it doesn't see air. Desiccation is never a good thing for long periods of time.> Thanks for your response.  <No problem, have a great one.  Jen S.> Sid.

How do I top off water in my Nano Reef? Hi Crew, << Hi there >> I have a 10 gallon saltwater tank. I replace 1 gallon every week. Since the weather has heated up the tank temperature started climbing into the low 80's so I got a small fan which keeps it around 78. But now I get a lot of evaporation, as much as a gallon a week. So I need to add a gallon of new unsalted water.
<< Yep, this is very common, just keep adding freshwater (not from the tap, but dechlorinated of course) as needed to keep the tank level filled. >> Do I still need to remove a gallon and replace it since evaporation does not remove any pollutants? << Yes this top off water doesn't count towards the water changes.  A 10 gal is very easy for water changes, considering one gallon of freshly mixed salt water is a 10% change.  Just be sure to slowly add the new water, make it is well mixed with the correct temperature before hand. >> <<  Blundell  >>

Evaporation effects >Re: my 55 gallon acrylic marine tank: when water evaporates, what goes with it? >>Pretty much H2O. >How bout ammonia, nitrates, phosphate, calcium, magnesium, iodine, etc. >>No, those are not evaporated away, especially the mineral substances. >And what are the benefits or disadvantages of having your tank mostly uncovered (power compact lights are maybe 4-5 inches above water level with high powered fan cooling everything)? >>The biggest disadvantages are losing fish (the jumpers), though this can be prevented by utilizing fiberglass/plastic window screening, and evaporation.  However, this is offset (significantly so) by the cooling effect of evaporation (it's much easier, technologically speaking, to heat a tank than to cool it), and the ease of gas exchange (O2xCO2) at the water's surface. >Also, it is true that if you have a window open your tanks pH will rise a bit, if so, why is that? >>This has to do with the pH lowering effects of CO2 (carbon dioxide), often experienced in closed up rooms with poor ventilation.  In Nordic countries this can become a significant issue, *especially* if heating is achieved via wood fire. >Ok, last question.  If marijuana smoking occurs within tank proximity, what are the possible detriments?   >>I have found that there are no detrimental effects observed (pers. exp.).  Of course, this is assuming that the room itself is relatively well-ventilated (no "Up in Smoke" recreations, please).  Cigarette or cigar smoke may pose more of a problem, ESPECIALLY if foam fractionation using a venturi-type air inlet is being used, as the smoke from the air can conceivably be pulled into the reaction chamber.  But with the wacky tobaccy, I think at worst your fishes will be feelin' a little groovy.  They may get the munchies, so have some Nori and other good-for-them snacks on hand, eh? >Your council's wisdom is precious to me.. >>This crewmember has spoken, the council may weigh in with other information.  Best of luck to you!  Marina

Evaporation Situation! Hi, <Hi there! Scott F. with you today> Thank you for all of the great info that you provide.  I searched through the FAQs, but I couldn't find an answer. <Okay- let's give it a whirl! LOL> I have a question that I hope you can answer for me.  I have a 90 gal SPS coral tank with metal halide lighting.  It evaporates approximately 1.5 to 2 gallons of water daily which maintains a 24 hr temperature between 78 and 80 degrees.  This water is replaced with RO ozonized water buffered with Seachem buffer.  All tank inhabitants are doing great and I have not had any temp related diseases such as ich.  Is this too much evaporation? <Well, any evaporation is too much, as far as we are concerned, right? However, in an open-topped tank with halide lighting, the usual reef pumps, etc., it seems pretty typical, actually> Should I invest in a chiller? <A chiller will help keep your tank temperature at acceptable levels, but it will not prevent evaporation. Your tank temperature and fluctuation seem quite acceptable. Short of hermitically sealing the tank (not an option!), diligent top-off seems to be the best way to go... Some people design and install automatic top-off systems, but they scare the heck out of me, really (I have no less than 4 friends who have had outright catastrophes, ranging from flooded homes to complete wipe-outs as a result of malfunctioning automatic top-off systems.> Thanks in advance for your response! Cheri Pawlak <My pleasure, Cheri. Just keep on top of things, and your tan

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