Water Stats

Gilli · Jan 8, 2009

I have a 9 month old mature tank. I have always used an underground filter which I recenbtly changed over to an external filter which was run in the tank for 2 months alongside the UG filter to make sure it was seeded. I then decided to take out the old underground filter as the gunk underneath wouldnt be properly aired when I turned it off for good, so I dismantled the tank gave it a thorough clean and put back new gravel and fresh decholrinated water. I was careful to run the filter in a bucket of tank water while doing all this.

After putting back the fish and plants and filter a few days later I tested the water and to my horror my results were

Ammonia 0.25

Nitrites 0.25

Nitrates 5.0

I immediately did a 50% water change.

I have taken readings 2 days running and my stats are now

Ammonia 0

Nitrites 0

Nitrates 0.5

Is this normal? I have never had an ammonia or nitrite reading since my tank was fist cycled 9 months ago!

doresy · Jan 8, 2009

Hi, a couple of questions that may shed some light.....

1) When you say you were careful to run the filter in a bucket of water you obviously dechlorinated that too, right?

2) Ok so if answer 1 was yes did you put the fish is this same bucket with the filter?

3) If the answer to 2 is no then there's your answer to your ammonia/nitrite reading.......my guess in this case would be that while the filter was running in this bucket of water the bacteria had nothing to feed on so some of it died. Then, when you set up again the bioload was slightly more than the surviving bacteria could handle causing what's known as a mini-cycle. Things should settle down now.

4) If the answer to 2 was yes then it was just that the filter was disturbed and they don't like that some times. Also, by "thoroughly cleaning" and the adding of new gravel you lost most of the tanks 'maturity' which was another likely cause.

Keep testing for a while to make sure......hope this helps you :good:

Gilli · Jan 8, 2009

Thanks for your reply

I ran the filter in a bucket of the old tank water which was decholorinated - I always do a 30% water change once a week with dechlorinated water - the tank cleaning process only took a couple of hours and the filter was running in a bucket of the old tank water all the time, so cant see how bacteria could have died?

I always thought that a long as the filter was seeded there wouldnt be any problems? I will shortly be upgrading from my 74L tank to a 250L (another reason I bought the new external filter) Ive been told on here that using 'fresh' water in the new tank wouldnt be a problem as long as it was a seeded filter so am I going to have even bigger problems when I upgrade

minxfishy · Jan 8, 2009

The slight blip would be due to the removal of the UGF, which was half of your bacteria source, therefore although the new filter had plenty of good bacteria in it, it was still relying on the some of the ammonia/nitrItes to be processed by the UGF, it would just take a day or two at most for the external to multiply enough to compensate for the removal of the UGF.