How long do I have to let the saltwater mix?

[aqh88]

Some organic material got into my water storage container and stuck to the powerhead where I couldn't see it. Apparently it's been breaking down in there for awhile because when I finally decided to test the water it was 50 nitrate, .5 nitrite, and 1 ammonia. I tested the source water for all those things and about a month back I tested the storage container for nitrates but since then I've only been testing the tank which kept testing high for nitrates. I've been doing water changes with that for my 20g and wondering why I could never get the nitrates down. Today I found my problem, scrubbed the container and powerhead clean, and just started new water mixing. I was told your not suppose to add freshly mixed saltwater to the tank but how long do I have to wait before I can use it? A few of the critters in my tank aren't looking so good and I can't do a water change tomorrow until evening so I'd rather not wait overnight.

[fish4dinner]

Are you using tap water for your saltwater mixture? If so, that's a bad idea since tap contains many of the elements and impurities you mentioned above (except for ammonia).

 

First, make sure you're using RO/DI or Distilled water to mix with the salt (i.e. Instant Ocean), and store that away in a closed container. RO/DI or Distilled water can be purchased by the gallon at a grocery store for about $0.75/gallon. Use an airstone or powerhead to keep the saltwater mixture sufficiently aerated. Generally, it's a good idea to allow the saltwater mixture to sit for 24 hours, but if you keep a steady reserve (10 gallons or more, depending on the size of your aquarium), you only need to worry about heating the saltwater to bring it up to the same temp as your aquarium water.

 

The key to lowering your nitrates is RO/Distilled water, reduce feeding, remove biowheels if your filter uses them, and change 10-15% of your water once per week. 1 PPM of ammonia is lethal to most fish; your ammonia level should always be 0 PPM, otherwise your aquarium is still cycling and unsafe for most livestock.

[Mr. Fosi]

I was told your not suppose to add freshly mixed saltwater to the tank but how long do I have to wait before I can use it?

 

I have heard a lot of talk about letting SW sit for a while before adding it to the tank. Often, the reason that is given is so that everything is fully mixed and the pH has a chance to stabilize.

 

That being said, I have added freshly mixed water to my tanks (only let it sit for 20 min or so) and never had a problem.

 

A few of the critters in my tank aren't looking so good and I can't do a water change tomorrow until evening so I'd rather not wait overnight.

 

If things don't look good, go ahead and do a change. Just make sure that the specific gravity and temperature closely match your tank.

 

Is your tap water chlorinated? If so, does your municipality use Cl2 or chloramine?

 

Have you tested your declorinated tap water for NO2, NO3, NH3, and PO4?

[Gill Snork]

I'm curious- what is the reasoning behind letting the water sit for 24 hours?

 

The salt is dissolved very quickly and reaches an equilibrium within minutes thanks to molecular diffusion and adequate agitation. And there shouldn't be anything left in RO/DI water that needs time to "settle out". And I highly doubt that anything in the salt mix needs time to do anything but be in water.

 

Are you sure this isn't just a carry-over from freshwater where you would leave tap water sit around for a while to let the chlorine come out of solution?

 

Chemically i'm not sure it makes much sense to wait any period past 10 minutes after the salt is adequately mixed and no more is left to dissolve.

 

Just my 2 cents....

[fish4dinner]

I'm curious- what is the reasoning behind letting the water sit for 24 hours?

 

<...snip...>

 

As Mr. Fosi stated, the reasoning behind allowing the water sit for 24 hours really has to do with pH stabalization. RO/DI, distilled, and even tap water tend to have neutral pH levels around 7-7.5. Ideally, pH in a saltwater aquarium should be 8.1-8.3. Your salt mixture contains buffers and other chemicals that set your pH to ideal levels, but this does not happen instantly. In reality, 20 minutes is probably enough time for the water to be safe enough to add to an aquarium, but for extremely sensitive corals and other inverts, it's safest to allow the water to sit for a day, so that you can test pH and salinity/S.G. levels in the saltwater mixture knowing that the water chemistry has stabalized.

[Mr. Fosi]

Are you sure this isn't just a carry-over from freshwater where you would leave tap water sit around for a while to let the chlorine come out of solution?

 

Chemically i'm not sure it makes much sense to wait any period past 10 minutes after the salt is adequately mixed and no more is left to dissolve.

 

I have seen from your other posts that you have a good knowledge of general chemistry and I don't disagree with your basic ideas regarding the speed of diffusion when facilitated by agitation.

 

I am, however, a little more cautious when dispensing advice to people here at NR. Some people keep very delicate things and don't always state that in their posts.

 

I, personally, don't feel a need to let my water sit for 24hrs, since I only have a FOWLR tank. I mix my water up in 5g batches; it is usually around a month before I have to mix up new water.

 

Before I did it this way, I mixed up seawater by the gallon as I needed it. When I did it that way, I let the water sit for 20 min while I brought it up to in-tank temperature, then added it all at once.

 

It takes a little time for the buffers and Ca2+ levels to stabilize and it may be worthwhile, in a coral tank, to wait a little while before adding the water.

 

EDIT: This 24hr stand-time could very well be a throw-back to FW husbandry technique. It may be unnecessary, but it is certainly not ill advised.

[neanderthalman]

I beleive the pH may have more to do with aeration, letting the C02 concentration reach equilibrium. C02 dissolved in water forms carbonic acid, lowering the pH.

 

I've done emergency water changes with saltwater that I had just mixed. I felt a potential pH shock was less of a risk than letting my corals stew in an ammonia filled cesspool.

[Mr. Fosi]

Yeah, the CO2 equilibrium makes sense.

 

As for pH shocking with a water change, you gotta figure that the pH has to swing at least as much once the lights go out at night...

[neanderthalman]

precisely my reasoning.....

[aqh88]

I'm using ro water. I don't even use the tapwater here for my freshwater tanks because it has so much junk in it and it has a ph of 8.6 which isn't good for most freshwater fish. The lid on my mixing container does not close completely because of the cords for the powerhead and the heater. I'm guessing maybe some floating plants from my boyfriend's nearby frog tank managed to get in there. The powerhead had brown junk all over the intake strainer. It's a 20g tank and I changed 6g last night after letting it sit for about 2hours and then mixed up 6 more gallons which I'm doing water tests on to be safe and then I'm going to start changing that. I'll have to pick up another 12gallons of ro today and maybe do another water change tonight. The tank only has inverts but it's been cycled for over a month. I just haven't found the fish I want and then I started having nitrate issues last week. Most of the black tunicate colony I got as hitchhikers died yesterday and last night and none of the featherdusters will come out even when I scatter bits of food over them. That usually makes them come out right away after a water change. I haven't been feeding the tank much except an occasional shrimp pellet for the snails and cleaner shrimp. The only thing that doesn't seem upset is this hitchhiking nudibranch that I'm worried about.

[Mr. Fosi]

Give us an update tomorrow.

[apophis924]

I have gotten away with watiing an hour, i used a powerhead and an air pump also. If you are talking "Emergency water change" then have to decide what is worse, keeping that water in your system until the "standard" 24 hour wait, Or change it out within the hour. If we are talking a serious emergency then changing it out ASAP will be better then letting such Emergency conditions exist any longer than nessceary.

[aqh88]

Nitrates are down to 25ppm. About 1/4th the featherdusters are back out and the shrimp are wandering around the tank again. It looks like the only deaths are half the tunicate colony which I wasn't confident I could keep alive longterm anyway. Nothing seems to care I've been adding water to the tank within about 2hours of the salt dissolving. My cleaner shrimp actually prefers to sit where I'm pouring water in and will move to get under the flow of new water.

[Mr. Fosi]

Good. Glad to hear that things are looking up.