Random Question

[superman1]

Hello

was sat at my desk thinking and it occurred to me.

are water changes neccessary if the tank water is already at

zero for ammonia and nitrates and nitrites..

as im guessing water changes are only if these parameters are getting to dangerous levels.

 

[bagu]

Its mainly too keep the tank clean and use fresh water; the fishes prefer it aswell.

Its like being stuck indoors; you need to get a bit of fresh air now and then so you go outside.

but the reason for water change/siphoning is to suck up debris and poop.

although 0 nitrAtes are very rare unless your tank is brand new =/

 

[oswoldy]

Fresh water also contains minerals that diminish over time so a water change tops them back up.

Mike

 

[OldMan47]

Zero nitrates are very common in my heavily planted tanks but they get a water change anyway. The fish and the plants need the other poisons removed from the tank and both benefit from a fresh dose of carbonate hardness to stabilize the pH and other minerals that the plants use to build new tissue. The fact that the nitrogen cycle poisons get all of our attention does not mean that they are the only contaminants in the water. They are just the hardest to deal with unless you have a proper biological filter.

 

[vinylman]

The one thing you have to remember with infrequent water changes is that the fish you have in there can become used to the conditions over time, while not appearing obviously unwell. The big problem would be adding new fish. These will come from a shop where water is changed weekly and very low in any potential toxins. Putting any fish from those conditions into a tank that is completely opposite usually results in a quick death for the new additions. IMO regular water changes are an almost free way of keeping a tank as healthy as possible.

 

[Inchworm]

As fish produce waste, and they turn to ammonia and then nitrites, the nitrates will rise. Doing regular water changes reduces them to safe and steady levels and bottom vacuuming eliminates harmful bacteria that might be breeding in uneaten food at the bottom. Water changes are always a good thing to do.

 

[Tolak]

Even if you have zero for ammonia, nitrites & nitrates in a cycled tank the fish are still producing waste, as you are feeding them. This can increase your hardness & total dissolved solids. Fish waste, by it's very nature, is acidic, and will tend to drop your pH. Nitrifying bacteria work less efficiently in an environment with lower pH. Ammonia is more toxic at higher pH levels.

So you finally get around to doing a water change after quite a length of time, your very lightly stocked tank has a nitrate reading of 10, so you figure it's time. Your tank water is now harder, and has a lower pH than your tap water. The change in hardness has more of an effect than the pH change for fish, if you take having to maintain an osmotic equilibrium into account. The pH change, and the water you are using to replace it which has a good chance of being treated with chloramine, does a number on your nitrifying bacteria, overloading it. Chloramine is a combination of chlorine & ammonia, a good dechlorinator changes this ammonia to ammonium, which is harmless to fish, but used the same as ammonia by your nitrifying bacteria.

But wait, your fish are still producing ammonia as well, the nitrifying bacteria is trying to deal with the ammonium, along with the normal amount of ammonia produced by the fish. The pH is higher, the ammonia more toxic. Houston, we have a problem. This problem is often called Old Tank Syndrome, which is most often associated with a very high nitrate level, in a neglected or very overstocked tank, but can occur in a less drastic form in a tank that is understocked.

The only way to get around this is with very heavy planting & very light stocking, look into the methods used by Diane Walstad if you are interested in this technique. Water changes are still employed to the best of my knowledge, but much less frequently.

 

[arobinson1984]

I agree with what has already been mentioned, even with fine water stat readins you should still perform a regular water change to keep the water fresh and prevent the fish from living in a 'toilet'

I personally do 50% a week on a weekend

Andy

 

[OldMan47]

Walstad's method relies more on using the plants to store the impurities and the plant trimming removes those poisons. It also relies on periodic water changes but not as often as an unplanted tank might use. Even the NPT approach does not say it is OK to just not do a water change because the nitrates are under control. Water changes are done anyway. I maintain an NPT and am moving to having more of them but I change water in that tank at least 3 times a year and I can never measure any nitrates in it. Nitrates are not the only poisons in our water supply. There are also traces of heavy metals, copper and other factors that we rarely think about because dealing with nitrates usually takes care of the rest of them.