Cant Get Tank To Cycle

[Mickfender]

Hi as title says i just cant get my tank to cycle, its a fluval 125, with a tetratec ex700 filter. I am on day 101 now, the ammonia has been going in 12 hrs for weeks now, but the nitrite is a real problem. A few weeks ago the nitrite was down to a trace only after 24 hrs, starting testing at 12 hrs was still high, then it just went up over a few days on 24 hr test while ammonia was still going in 12 hrs.The tank has quiet a few plants that are all doing well,so i changed about 90% water,cleaned tank and glass but did not touch the filter,then the nitrite started going down again slowley. 5 days ago it was cleared in 24 hrs , the day after the same,for 2 days i could not do test on 24 hr slot but i still topped up the ammonia to 5ppm, then yesterday nitrite is back to 5ppm on 24 hr test and the same today but all this time the ammonia clears in 12 hrs no problem. Any thoughts on this would be a help thanks Mick

 

[N0body Of The Goat]

What pH is the tank water? Since I started the hobby in March, there has been a common theme of pH >7.5 that seems to stall the nitrite processing bacteria in several tanks in this forum.

You could get a carbon dioxide system for your plants' benefit, which would lower the tank pH (amount of movement dependent on gH eg. gH of 14 gave a reduction in pH from 8.2 to ~ 7.5 with 30 bubbles per minute during daylight hours).

Another thought that comes to mind is that you do not mention nitrate readings. If the concentration of nitrate gets too much, its quite possible that this could be toxic to the nitrite processing bacteria (just like when making wine at home, the yeast can be killed off by getting too high a concentration of alcohol in the solution).

 

[Mickfender]

The ph is 7.8 at moment was 8.2 a few days ago going down now, ive added bicarb to ring up ph this was about 2 weeks ago.

 

[OldMan47]

There should be no reason to add the bicarb unless your pH goes below 7.0 Mick. I would watch what you have already accomplished in terms of moving nitrogen. The move from ammonia to nitrite is very significant and seems to be behind you. The move from nitrite to nitrate seems to lag behind quite a bit. My own experience is somewhat limited to only showing what will be needed to move the nitrite on to nitrates. One thing we seem to see over and over is that people having trouble moving their nitrites to nitrates seem to do better after a water change that returns the nitrite to a value that people can actually monitor. While nitrites are beyond being measured, folks seem to have more trouble getting a nitrite processing started.

 

[Twinklecaz]

Sorry can I butt in and ask you 2 something.

I keep getting Nitrite and Ammonia readings. Ammonia I'm aware is prob a false reading coz of my plants ferts but the Nitrite was confusing me till I saw this this...


I've recently upped my dosing of Easy Carbo to prob what is overdosing to try and sort my plants out. I have noticed that my PH has been a bit lower (maybe 6.8 at times) but didn't connect the 2. Is is possible that the EC has lowered the PH and stopped my Nbacs from working properly?

My tank's been cycled for near on 2 months and never really had any probs before now.

 

[OldMan47]

Hi there Caz. A high tech planted tank is entirely different from the discussion we are were having here. Your EC dose has almost nothing to do with the nitrogen levels in your tank. Instead the ammonia and nitrite readings are really related to the levels of processing being done by your filter and the amount of ammonia that your plants can remove from the water column. Since plants are well known to remove ammonia from the water column, the processing of ammonia is a poor indicator of your cycle's maturity. Instead the processing of nitrites will give you some insight into the cycle's progress.

 

[waterdrop]

Yes, I agree with OM47, it feels like gravel-clean-water-changes are in order here. Despite it being a fishless cycle, deep cleaning the gravel (where more nitrate hangs out and helps to slow N-Bac development) and large water changes (perhaps on weekends or when its convenient) should not only accomplish getting nitrite in range as OM is saying, but of course will also clear a lot of nitrate and make a fresher environment for the bacteria. Unfortunately, our bacteria are just like our fish in a way, they both really like huge (thousand, million gallon) environments like those of nature much better.. in the case of the bacteria it can be like having their cake and eating it too in that pockets of strong ammonia can flow past the bacteria but then be washed free by lots of fresh oxygenated water. By comparison, our tiny tanks and filters will always seem to be a slower and more stagnant environment in a way. Anyway, in my experience, water changes in the latter stages when a fishless cycle gets long can't hurt usually and often help.

Also agree with OM's reassurance to Caz about the Easycarbo - in my experience liquid carbon dosing is not something that should cause worry about ones filter bacteria. The business of pH crashes during fishless cycling has more to do with quick pH drops often caused by the large ammonia doses that create relatively more nitric acid component. Now that your tank has fish and the overall changes are slower, the bacteria should be fine even though the pH gets pretty low. The autotrophs can still do their thing even in low pH tanks. Trace ammonia and nitrite still showing up may be more a function of the filter's mechanical aspects, or at least that's a possibility I suppose.

~~waterdrop~~