Unexpected Ammonia Spike

[arobinson1984]

My 35 gal tank has been up and running for over a year with no probs at all regarding water quality.

About 10 weeks ago I added an eheim 2075 and seeded it alongside the jewul internal for 6 weeks, then took the internal out and put one of the sponges from the internal inside my eheim.

On saturday, I had abit of spare time so on the off chance I thought I'd do a water test with my API master kit (I usually test on sundays) to my amazement the ammonia reading came out at 1ppm, I've never had trouble before. I noticed a couple of fish were missing and after 20 mins routing I found them both dead (possibly the cause of the ammonia / cause of death)

I took out the two dead fish, did an 80% water change and tested an hour later, everything fine, ammonia down to zero.

Anyway on sunday I did my usual test, again the ammonia was a little high, about 0.50ppm this time. All the fish have been accounted for so there are definately no more dead fish. I did another 80% change and after an hour ammonia once again read fine back to zero.

I have tested this morning and once again ammonia was at around 0.50ppm so I've done another 80% change this morning (lucky I've got a python lol)

Anyway, only changes to tank recently are:

* 1 BN plec was added about 2 weeks ago, thats the only fish added in the last 3 months.

* I've started adding Seachem flourish excel liquid carbon for my plants, cant see this causing any probs.

* On sat I added 2 x hikari algae wafers for for the plec although all the fish were eating them and there is no trace of them left and out of the 3 water changes I've done, I vacced the gravel twice to make sure.

* I added 1 dose of Interpet no 9 last week for internal bacteria (the fish is ok now) would this harm the filter? its says on the box that it doesn't.

* A plastic ornament added about 2 weeks ago that was bought from lfs.


Any ideas what may be causing the ammonia spike? I also checked my tap water which as expected is coming back as zero for ammonia.

Nitrite readings have been zero every day, only ammonia reading is being affected.

Thanks in advance for any suggestions

Andy

 

[minxfishy]

The fish may have died naturally, but being still in the tank would have started to rot, therefore causing an ammonia spike. The adding of plec, would add extra bio load as they are messy fish, so coincided with the fish dying, would have raised the ammonia levels too.

Are there any plants rotting, even slightly as this can cause a spike too.

 

[arobinson1984]

I know the BN plec will add a little to the bio load but hopefully this will be evened out by the fact I lost 2 fish so the bio load should be around the same.

The 2 dead fish were taken out on sat and I've had 2 days since of high ammonia readings so I think that may have been the original prob but doesnt explain sun and mondays readings after taking them out on sat and doing an 80% change.

One of my amazon swords has a bit of black brush algae on it and is going slightly brown on the edge of just one of the leaves, I wouldn't consider it to be 'rotting' but I may break off that leaf anyway.

Thanks for the advice, any other suggestions are welcome

Andy