water change

[Anonymous]

I read somewhere that prior to a water change, one should mix the salt and let the solution stay overnight, or better yet, to aerate it overnight, does anyone know why this practice is being done?

Incidentally I'm talking about changing water in my FO tank and using water straight from the tap, and adding PRIME to neutralize chloramine. Isn't there more oxygen from the tap water than the old water in the tank?

What's the benefit of doing it?
What's the harm if I don't do it?

Appreciate any responses,

Peter

 

[Anonymous]

Hi Peter,

I believe that there are 2 common problems with using really fresh water. First, many municipal water companies add CO2 to prevent pipe degradation. Many people with reef tanks attempt to get the ratio of dissolved gases close to their equilibrium values. Second, the salt can take a long time to dissolve completely. So you can have salt that visually appears dissolved, while under enough magnification you'll see that the salt crystals are still floating around. Undissolved salt can probably be a bit caustic to your animals.

 

[Anonymous]

There are a number of chemical reactions that can take place in freshly made seawater that you might want to happen before you add it to the tank.

The primary one usually talked about is equilibration of the carbonate/bicarbonate buffer system with atmospheric CO2. This will help stabilize the pH and alkalinity of the water to be added to the tank.

A second potential reaction is the precipitation of certain heavy metal contaminants. These come in as impurities in some of the ingredients, and given the chance, some may precipitate from the mixture (which would be good). This may or may not happen in the time allotted.

I'm not sure about the oxygen comment. Why would there be more O2 in the tap water? You don't think your tank is at saturation? In any case, it's not the primary reason for the prescribed aeration. Bear in mind, however, that tap water may well be deficient in O2, depending upon its source.


------------------
Randy Holmes-Farley

 

[Anonymous]

Hi Peter,

First off, don't use your tap water for water changes or top offs. Most municipal water is not suitable for saltwater tanks. I live in Southern Califoria and the the water is not fit for human consumption, let alone the very sensitive reef organisms.

Just mixed saltwater can be harmful to your fish. Usually the mixture is not fully dissolved, and the water you put into the tank can be of too high a PH or too low. I have heard of fish being "burned" because of the undissolved chemicals coming in contact when the water is added. The best thing to do is to put an airstone in the container and let the saltwater completely mix, as well as oxygenate.

To summarize:

1. Don't use tap water. Either go to your LFS and get ocean water, get a RO/DI unit or use sparkletts.

2. Let your new saltwater "age" for a day or two in a container with aeration.

Good luck!

 

[Anonymous]

ok guys, thanks for the replies.

Any idea how I can mix 4 bags of salt in a 40 gal trash can (I usually change about 200g of water once every 1.5 months) and totally have the salt dissolved in a day or 2?

 

[Anonymous]

Check C. Bingman's site for a description of a propeller attachment for a drill to aid in dissolution. (I've never tried it) He says that you can mix and aerate saltwater in less than an hour.

Since I happen to have a catalog in front of me, it's available through US Plastics (www.usplastic.com) and is listed as #85062 for $13.23

It's an 18" rod with a 3 blade propeller, constructed of steel and covered with polyethylene. The blades are 1.75" in diameter. It should fit on a standard drill with no modifications.