Toxic gravel?

[gpdiver]

My 200g tank was running well for 6 months. Two weeks ago after a 50-60% water change, I lost half the fish in the tank. The ammonia and nitrites were through the roof. Apparently the bilogical filter was affected. I used a python and dripped Amquel in. Anyway after a few days the tank showed signs of cycling again with a hazy white appearance then clearing. I have since changed to letting the water change water age a day ahead in a rubbermaid trash can.

I kept my 36w uv running during this. The water is clear now, but I noticed that some of the sword plants have holes in the leaves and there is a dsitinct odor of hydrogen sulfide in parts of the gravel. Also, the vals all died and the roots were black. I've tried to poke the gravel in parts to help release any hydrogen sulfide. Some plants are fine, except for the holes in some swords.

The ammonia levels are still very high .5 ppm and the nirites are only slighly present at .25. I would have expected the ammonia to start declining as the tank is fully stocked with plants, I have 2-3 w/g of compact flourescent lighting and am dosing ferts. The tank conditions are as follows:

No3 15-20 ppm (adding KNO3)
phosphate 1-2 ppm
CO2 35 ppm (verified with lamotte CO2) also goo dplant pearling
added extra potassium as I thought the holes were due to this
KH= 9
GH=11-12
Subtrate is 100% ecocomplete.
2 EHEIM PROII filters

I just turned off the uv this evening as I am concerned this may be interfering with the cycling. Starnge thing is the remaining fish seem fine despite the high ammonia. Also, i checked the ammonia with 2 tests: Salifert and Sera and both match the high value.

Any suggestions?

 

[Tom Barr]

Re: Toxic gravel?

Vac 1/2 the substrate and do 50% water change.
Repeat the following week.

Something killed the plants./stop them growing, eg CO2, poor nutrients or both. NH4 at 0.5ppm will not harm things.

So keep up on that and this will help.
I've seen this occur a few times over the years.

But...........did you add the right Amequel etc after the water change?
Is the tap changed any?
Does the tap have Chloramines or Chlorine or did they recently switch?

Regards,
Tom Barr

 

[gpdiver]

Re: Toxic gravel?

When the problem arose 2 weeks ago I added double the amount of Amquel (using the kind that removes chlorine and chloramine). I was using a python and dosed the amquel before and after with enough to treat all 200g. I had the filters running while doing the change, so I'm wodering if the tap water got in before the Amquel removed the Chlorine (water co. uses chlorine). I did do a larger water change (60%) as i was pulling and trimming a lot of plants. Is it possible for too much Amquel to distirb the biological system?

Since 2 weeks ago, I now prepare 30-40 gal the night before in lg trash cans and measure the Amquel in.

Any idea if the uv (fairly lg at 36w and only 200 gal/hr moving through) could have been preventing the tank to cycle since?

 

[gpdiver]

Re: Toxic gravel?

It looks like the tank is cycling now. The NH4 dropped steadily since turning the uv off.

 

[Tom Barr]

Re: Toxic gravel?

Good, something and it was not the tap, added the NH4.

Clean the tank etc, I've never had any associated issues with Amquel and tap water and I've done large changes all my life.

Plants or not.

Regards,
Tom Barr