Help!! newly cycled tank crashed

[pmarr90]

Hi,

I recently set up a 98l aquarium. the tank fully cycled and everything was going great. Then it just sort of crashed. the ph dropped and the ammonia climbed slightly.

Any ideas what happened? and what can I do?

 

[sinibotia]

How often do you do water changes?

 

[pmarr90]

Once a week 15 - 20% of the water.

 

[adjustment]

Added fish too fast or wasn't fully cycled?


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[sinibotia]

How heavily stocked was it? And how did you cycle it?

 

[pmarr90]

2x platys 4x danios 3x mountain minnows.

This tank was an up grade, the dealer that I go to gave me seachem stability and said if I used this in the tank for a week that the bacteria in the tank shuld have built up enough for me to put the fish in.

Like I said this seemed to work until recently. New fish have been added but according to the guy in the store the stocking levels are still safe and shouldn't have caused any issue.

 

[libertybelle]

did you stop using sachem stability? Could be the added bacteria were taking care of the ammonia but hadn't actually grown up in the filter enough yet to deal with it without the additives

 

[sinibotia]

Yeah your stocking levels aren't the issue. I suspect it's a problem with the stability supplement. Some products like that have the wrong bacteria and so they won't establish in your filter at all.

 

[ScotJudd]

I agree with the comments above. Bacteria supplements can deal with the ammonia even if the bacteria is not in the filter. Stop the supplements and the tank crashes. I don't hold with adding bottled bacteria myself, seeding the actual filter with media from an established tank is the surest way of getting the bacteria where you need it - in the filter.
A ph crash is common when cycling especially if your Kh is too low. You didn't say what the Ph dropped to. If it was 6.5 or lower then this itself will hinder the development of beneficial bacteria. If the Kh is too low, below 5 deg, then the water hasn't the buffering capability to avoid an acid crash. Have you tested your Kh?


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[pmarr90]

Ah, that all makes sense actually. I did stop using the seachem. So do I just allow the tank to cycle naturally from now on or is that to risky for the fish?

The PH generally differs from 6 to 6.3 on my chart.

 

[sinibotia]

Ah, that all makes sense actually. I did stop using the seachem. So do I just allow the tank to cycle naturally from now on or is that to risky for the fish?

The PH generally differs from 6 to 6.3 on my chart.

I would add some crushed coral sand to your tank, maybe in a mesh bag in your filter, at least temporarily to increase your kH; if your pH is 6 then your kH must be very low.

Otherwise yeah, allow the tank to cycle normally.