Large Water Changes and Tank Cycling

[CammieTime]

Does doing a large water change make your tank go into a mini-cycle? Obviously the concentration of ammonia is reduced with a large water change, which would kill off some beneficial bacteria until the ammonia concentration returned to pre-water change levels. If so, your tank never really "cycles" if you are doing frequent large water changes.

[Adam S]

Not in my experience. I suppose it could happen if you do something wonky like 100% water changes once a month, but even a lackluster maintenance schedule can keep things in line for a while.

[Ryan925]

Does doing a large water change make your tank go into a mini-cycle? Obviously the concentration of ammonia is reduced with a large water change, which would kill off some beneficial bacteria until the ammonia concentration returned to pre-water change levels. If so, your tank never really "cycles" if you are doing frequent large water changes.

Large daily changes are a staple of discus keeping.

[Filip]

Nitrosomonas and nitrobacter live and " work on our side " in colonies inhabited on a slime formation formed strictly on surfaces .
They are fairly inactive and scarce while they are motile in the water column .
That's why you don't have to worry about the few motile BBs in your water column , because most of them thrive and work in the colonies on our filter materials and in the sand bottom , if you have one .

[CammieTime]

Nitrosomonas and nitrobacter live and " work on our side " in colonies inhabited on a slime formation formed strictly on surfaces .
They are fairly inactive and scarce while they are motile in the water column .
That's why you don't have to worry about the few motile BBs in your water column , because most of them thrive and work in the colonies on our filter materials and in the sand bottom , if you have one .

Yes, but if the ammonia concentration in the water column changes frequently the bacteria cannot maintain at a constant level beacuse their food source is eliminated with large water changes. It may take days to return to the previous ammonia concentration, in the mean time the bacteria are starved and die. That is my point.

[Adam S]

There won't be much ammonia to begin with if you do water changes regularly, and there is much more to bio filtration than a couple species of bacteria. Besides, the bacteria involed with ammonia processing double in population at least once a day.

[DJW]

Yes, but if the ammonia concentration in the water column changes frequently the bacteria cannot maintain at a constant level beacuse their food source is eliminated with large water changes. It may take days to return to the previous ammonia concentration, in the mean time the bacteria are starved and die. That is my point.

When there is no ammonia, the ammonia-oxidizing bacteria don't instantly drop dead, like a car running out of gas. I have three fishless tanks cycling most of the time (experimental tanks) and I often don't add any ammonia for a couple of days after the ammonia is gone. They go dormant... the bacteria need ammonia mostly for energy, and not necessarily for short term survival. The fish are continuously excreting ammonia from the gills, even during a WC, and in a cycled tank the bacteria are oxidizing it at the same rate it is being excreted.

[CammieTime]

What if you change 80% of the water twice a week...the ammonia concentration will be quite high by water change day and then drop significantly after the water change...this does not impact the beneficial bacteria in any way?

[Adam S]

You're worrying way too much about beneficial bacteria. Twice a week is fine.

[Filip]

What if you change 80% of the water twice a week...the ammonia concentration will be quite high by water change day and then drop significantly after the water change...this does not impact the beneficial bacteria in any way?

There isnt and there should'nt be no Ammonia nor Nitrites -No2 detectable in a well established tank and filter . Only nitrates -NO3 should build up between WCs.

BB colonies in your well established filter materials takes care of ammonia very quick if not instantly . They are in constant change of numbers and constant equillibrium with the bioload / present Ammonia. Their numbers constantly change and vary in correlation with the present ammonia levels.
They multiply quick and DOUBLE their numbers between 7-14 hours .
On top of that as DJW -Dan already said , fish constantly release ammonia and BBs don't instantly die off in large numbers when left with less food to eat for just a couple of hours .

[bluelagoon]

Altho,you can have ammonia spikes if you over load the bioload with anything organic.Excessive food,more fish,vodka ect. and causing a slight cloudiness to the water.

[Filip]

Altho,you can have ammonia spikes if you over load the bioload with anything organic.Excessive food,more fish,vodka ect. and causing a slight cloudiness to the water.

But how and why Vodka in our tanks, Mervin :) ?

[CammieTime]

If you do a large water change (say 80%) at bed time and do not feed the discus until the next morning, the massive BB colony will not starve overnight? It can survive for hours on fish created ammonia alone?

[Adam S]

Yes. You cannot harm your bb colony with water changes.

[CammieTime]

Yes. You cannot harm your bb colony with water changes.

But you can harm it if you siphon out all the gunk and uneaten food on the bottom of the tank during a water change and dramatically reduce the colony's food source.

[Adam S]

I disagree with that entirely, but the hobby is about doing what makes you happy.

[Altum Nut]

I'm just reading this and it was not mentioned unless I missed it but are you using straight tap and do you add conditioner? If your water source has high levels of chlorine/chloramine...large w/c's at 80% might have a slight affect the BB and more so if your squeezing out sponge media at the same time with tap water.
Just covering the common errors...but if all above checks out and does not apply then I would agree with the others saying that your over thinking this and would not stress out.

...Ralph

[bluelagoon]

But how and why Vodka in our tanks, Mervin :) ?

I used it in a planted tank to dose some sort of carbon to the water instead of Excel.Seemed to work ok.But did notice slight cloudiness if I used a bit too much.

[Filip]

I used it in a planted tank to dose some sort of carbon to the water instead of Excel.Seemed to work ok.But did notice slight cloudiness if I used a bit too much.

This is new for me and quite interesting Mervin .

How much did you used and did you see any adverse effects on your fish or filters? .
Did you noticed plant pearling , PH lowering or any other sign that lead to conslclusion about increased co2 levels in the water , using this method ?

[CammieTime]

Here's the deal. Large water changes will not impact an established beneficial bacteria bed, but they will dramatically SLOW DOWN the process to cycle a tank (really the filters) or a tank going into re-cycle. So, lesson learned is that if you are having ammonia issues frequent large water changes will keep your fish alive, but they will not cycle your tank very quickly (may take months). Fastest way to done is to setup another tank with a duplicate set of filter media and cycle that using waste water from the main tank, and do very few water changes on it, and add ammonia as necessary - you want to replicate the bio-load of your main tank. This process should take the standard few weeks since you do not have to change the water. Soon enough that new tank will cycle at which point you can put the cycled filter media into your main tank. In the mean time, change water heavily on your main tank to keep the fish alive.