Mini Cycle

[MatthewLP]

Mini Cycle Questions,

I have a 90 gallon discus tank. I just finished adding my schooling fish cardnals and some harliquin's and my one 1 mellon discus came 2 days before the others did.

Anyways My tank is done cycling and I'm showing my increase of nitrates ok but every time I do a 50% water change twice weekly I get a constent spike in ammonia and Nitrites. I use prime to dechlorinate my water and the ammonia I'm sure is being turned into ammonium but it clears up in 24 hours or less and I get zero of ammonia. But my problem is my Nitrites. I get a slight flair up .25 or less every time I just do a water change. I don't mess with my filter or clean the gravel just any loose top debris and thats it. it takes a few days again before my nitrites go back down to zero again. I'm showing plenty or nitrates so I know the conversion of ammonia to nitrites to nitrates is going on.

I'm not understanding the flair up of nitrites just changing the water only. is my healthy bacteria that weak? or is there any other cause of this?

I have healthy media for my other 55 gallon is some panty hose thats still in my 90 and I'm still having these flair ups.

[DonMD]

I've had spikes before, but usually after meds or something like that.

The only thing I can think is that either your filter may not be large enough (not enough bio-media), or your fish load is too large (too many fish).

Other than those guesses, I wouldn't have a clue. Good luck!

[Chad Hughes]

Matt,

If it only happens after a water change, I would look at your tap water. Prime will show a false positive for about 24 hours. After that, prime is depleated and your test should show no ammonia unless you have a biological filter problem. Nitrates (at low levels) should not be an issue but nitrites should never show. Is it possible that you show nitrite in your tap water and your biological filter consumes it after 24 hours?

Hope that helps.

[MatthewLP]

Matt,

If it only happens after a water change, I would look at your tap water. Prime will show a false positive for about 24 hours. After that, prime is depleated and your test should show no ammonia unless you have a biological filter problem. Nitrates (at low levels) should not be an issue but nitrites should never show. Is it possible that you show nitrite in your tap water and your biological filter consumes it after 24 hours?

Hope that helps.

Thank you for you responce.

Ok if prime is depleated after 24 hours that explains my API false positive.

Now on to the nitrite issues. per your request I tested my tap water for Nitrites and its test at zero and stayes at zero. So its not in my tap water.

I tested nitrites again in my 90 gallon and yes its .25 still. It seems to take a few days for it to reach zero very slowly and by that time my nitrates are high enough for me to do a water change again, becuase its start around 10ppm after a water change and reaches to 20ppm or higher so I know its working some where. I'm just wondering in the Nitrite bacteria is to week to keep up or if its stalling some where. I just can't figure out why.

I've added more Gravel from my 55 gallon to help with the Nitrite colony and see where that goes. I may add tetra's safe start again to build up my bacteria colony too if I don't see any progress in a couple of weeks.

This only happens after I do a water change. if I leave well enough alone it keeps up and my nitrites show zero..but as soon as I do a water change it takes severl days before my bioload to catch up again.

Yes its a faily new cycled 90 gallon, I'm going though that brown algae stage but its not out of control. it's just on sponge filter and fake plants.

My PH is around 6.8 I wondering if the the PH is more on the acid side if thats the problem.

anyone have any suggestions or ideas?