Best Way to Replace Evaporated Water

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Aquarium Advice FINatic
Jun 9, 2004

What's the best way to replace evaporated water? I know you should use fresh water unless you are trying to adjust the specific gravity, but what should I do to prepare the fresh water?

Use RO/DI water with low or no TDS. You should have a daily average evaporation rate.
If you dont have an RO unit you an get RO water from most good LFS's or from a local grocery store. Stores here in the US have RO dispensors you bring a water jug in and buy by the gallon. I dont know if they have those in Sydney or not.

If you are using regular tap water then I would put tap water in a bucket with some declorinator and let it airrate for 24 hours. Then just add it to the tank. The level of water one usually puts in for daily or bydaily evaporation isnt going to be enough shock the fish with a low temp so no real need to bring it up to tank temp. If you have a sump clearly you should add the water to the sump and let it mix with the existing water before it gets to your tank. If you dont have a sump then just slowly pour the replacment water in the tank in a location that does not have coral/fish.

Now something I always experenced is my fish would come over and check out what I was doing so its almost imposslbe to add water to the main tank with out having the fish in the way. ;)
FF wrote
put tap water in a bucket with some declorinator and let it airrate for 24 hours.
If you are using CITY water (public supply vs a well), it is most likely chlorinated water. You need to aerate it for 24 hours to break down and remove the chlorine. The dechlorinator will help break down and remove chloramine/chlorine.
I say this with the full knowledge that I will be attacked by several die hard people on the board. However, I say this with the knowledge of my chemistry degree, and half a decade of work in biomedical research. chlorine is highly over rated. Chlorine is a gass (Chemically represented as Cl2). Therefore, there are many ways of quickly removing it. I have friends who have raised 10-15 generations of discuss, doing approximately 25% water changes daily (no filter aquariums) without ever letting the water sit, or using a dechlorinator, and we all know how needy discus are (this particular person has a PhD in chemistry, and worked as a head researcher for Pharmacia). Second person I know has been raising angelfish (about 15 different variants) doing the same technique. No mortalities in both. I used fresh water for when I was breeding seahorses (no need to worry about TDS concentrations rising with high water change rates). The way all three of us accomplished this is that we simply used an airation method as we were pouring. In other words, we held our finger over the hose and let the water jet into the aquarium, driving the chlorine out, or we simply used a sink (most sinks in the US, with the exception of laundry sinks have a built in airation piece, that mixes the water with air to drive out chlorine, making your sink water look white, as opposed to the clear you get out of a hose.) However, if you want to apply this technique, I would advise to call your local water board, and find out if they use chloraime. This technique SHOULD work for cloramine, but I have never tested it, and would strongly suggest that you should not test it on your prized fish, or reef tank (if you don't use RO/DI which for that you really should). It would be worth it to study this issue further without following what industry tells us. After all, dechlorinators are a multi-million dollar industry, and I know I speak for myself when I say that I can use every dime to further my aquarium addictions.

Andrej Spec

ps. I say this to encourage debate, not to insult anybody, or make them feel like they are in the wrong. If anybody has any concrete evidence (not anecdotal) about this, I would be more than interested to read about it.
Okay so basically when I read the posts above, and cross reference them with the LFS I can basically use the water from my tap as long as I treat it for chlorine and chloramine, and let it air for a while it should be fine. I'm only replacing a small amount of water (perhaps, 5-10 liters). I should also try to "air it" as I enter it into the water so that the chlorine can escape.

Please tell me if this is incorrect?
What type of setup do you have? The well explained post above takes care of the chlorine problem but you can add other things that may hurt your setup. The tap water can add phosphates and or nitrates. Test your source water and you may not have any worries.

When I had a fw tank I used a Meridian dual hose water exchanger. It had a restricted flow jet nozzle for the inflow that completely aerated the water from the tap. I would hook that up to my sink and do water change over an hour or two and never had a problem.

With tds of 180-235 from my tap I much prefer to use RO/DI water for water changes.

Thanks for that explanation.
Totaly agreed. I have the same water exchanger too. I use it to change the water of my oscars. I leave it on all night, and all day, and there is approximately a slow gradual 100% water exchange over 30 hrs or so. They work really well, and I know people who used them for discus, so you KNOW the chlorine is gone.

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