Water Change Question?

Question

My tank was fully cycled quite a while ago. Now though my levels never rise, Ammonia, Nitrite, and Nitrate, stay at basically zero at all times. About my tank: In my 20 gallon tank I have 20 things, and the filter is a bio-wheel actually meant for a 55 gallon tank. The water always stays crystal clear. (I know what a horrible problem to have?)

So do I still have to do the water changes? Or are water changes unnecessary unless the levels start to rise? Is it safe not to do any water changes until the levels rise?

Answer 1

Okay, your tank is cycled, but have you added fish? You say 20 "things", so I have to wonder that these things are. If they're small snails, or freshwater shrimp, they may not be producing as much waste as a fish. If the things are decorations, no waste at all. Unless there's an ammonia source, the bacteria from cycling your tank will die, so when you add a fish, it'll be just like not having cycled at all.

If you do have fish, you'll still need to do water changes. Ammonia, nitrite, and nitrate aren't the only things produced by fish wastes, but the first two are toxic to your fish, and all are capable of being removed by bacteria, algae, or plants. Not all are. Plus, you're adding calcium, magnesium and other elements that can be useful to your fish by doing a water change.

Answer 2

Yes, you still need to do water changes. If your Nitrate is 0, the tank is not cycled. I maintain aquaria for a living. I do 15+ tanks a week for over 4 years now. Not once have I seen a cycled tank have a 0 Nitrates.
You might only need 10% every 2-3 weeks, but sooner or later, the nitrates will go up...
Having an oversized filter, not over stocking, and not overfeeding go a long way to keep aquarium maintenance less frequent.

Answer 3

Probably the water change stirred up additional nutrients from the gravel and fed the green water even more. Do another water change of about 50% while cleaning the gravel well. Keep the lighting down to about 8-10 hours a day and be sure to prevent any sunlight from hitting the tank. Cut back on your feeding for a few days and then do another 25% water change and clean the filter. You should see the green water getting much better in a few days and clear up well within 2 weeks. Please avoid using any type of algae killing or water clearing chemicals. They are simply not worth the money and not worth the damage they do to the tank in the long run. MM

Answer 4

The usefulidiot has a good point - nutrients and vitamins in the actual water get used up by the fish, and changing the water is the best way to replenish them.

It's impossible for the nitrates to be 0 unless you have a heavily planted tank that uses them faster then they appear. The whole point of biological filtration is to create nitrates from nitrites (and nitrites from ammonia). So, if your tank is not heavily planted, and you really are testing 0, you had best get a new tester.

No matter how you look at it, fresh water is good for your fish. I don't care how clean my tanks look, I'll do my weekly water changes - the fish are worth the small amount of time it takes.

Answer 5

water changes are always necessary, no matter how crystal clear ur water appears. think of it this way. everyday u lose water due to evaporation. however, the amount of solutes in the tank remains behind. in fact, it's increasing thru the metabolic processes of the fishes/animals in the tank as well as less water in the tank. even if u top off (replace) the evaporated water with distilled water, the amount of solutes dissolved in the water constantly increases. pretty soon, ur crystal clear water is overly saturated with solutes. that's a recipe for disaster.

Answer 6

Water changes are important not only for controlling your levels, but also replacing key elements in your tank that get depleted over time. So you probably still want to do a water changes.

Answer 7

You need to vacuum the debris from your gravel bed. It's not healthy to leave detritus in the tank. Even if the water quality is fine now, this stuff is decaying and producing gas bubbles that might escape at any time. It really needs to be removed. Whether you need to actually remove water at the same time, that depends on who you ask.

Answer 8

You still need to change the water around once every other week as the fish(or whatever) waste will pile up and the tank will get really dirty, but actually it sounds perfect!

Answer 9

Just make sure you vacuum every other week or the waste and extra food will cause ammonia spikes. When you vacuum you will need to replace the lost water, so that would count as your water change. It may be less than what other tanks need, but it's still necessary to vacuum and replace the lost water.

Answer 10

Yes you still do. Waste builds up from fish, not a healthy thing to have in the tank. Nitrates if as you said your filtration is outstanding is going to soar, so you need to do weekly changes to keep that low. You shouldn't need to do massive changes 25-30% should be fine, but bounce your nitrate readings after changes against it. If you are not zeroing out, then do a bigger change, up to a 50% change. Plus water changes give you a chance to add in a good dose of aquarium salt which helps keep good health in there.

JV