Old tank Syndrome- Extremely High NITRATES
Hi All, Iíve had my 105 for 6 years now and the Nitrates are extremely high- 80-120 PPM and I donít know what to do. The highest itís ever been was over 160 PPM a few months ago. Although I have tried a few processes to minimize it, but Iím sure it must be old tank syndrome. 18 months ago I removed and replaced all the biological media from the Eheim Pro 3 (Eheimís biggest Canister) thinking that this would help, unfortunately I did not test frequently after I did that, so I do not have any data, but I donít think it helped much. The test kit I use is API, it was purchased recently and I followed a process on YouTube on the proper way to test.
ē 1 month ago I removed all 200 lbs or so of the original Seachem Flourite dark substrate (from 2014) and replaced with Seachem Black. I thought the substrate was a nitrate trap, and surprised that it was not.
ē I do 50-70% water changes weekly.
ē I replace the dense foam pad in the canister about every 4-6 weeks or so, Iím thinking I should probably replace more often, but I donít like to break into the Giant canister filter every time I do a WC, itís a PITA.
ē I dabble back and forth between PPS Pro and EI dosing, but try not to overdo it.
ē I have a dedicated skimmer canister filter Eheim Classic 350 just for extra filtration and skimming. I have Seachem Matrix filtration media and foam media in the 350 Classic.
ē I have 2 T5ís and Fluval 3.0 for lighting, if that matters. I constantly mess around with the lights to try to dial them in.
ē The fish bioload is low, 12 small tetras, the nitrates were very high even when the tank was fish-less for a few months (160 PPM). I have good water movement via an MP-10.
ē I dose C02 with a Cerges reactor, about 3 bubbles per second. Bubbles are completely dissolved prior to entering the tank.
ē The plants that are red in most tanks are brown or copper/green in mine indicating high nitrates especially for the rotala.
ē Phosphates at 0. Not worried about ammonia or nitrites since it is 6 years old
ē When I filled the aquarium up after it was completely emptied of everything, I used fairly warm water, probably 85-90 degrees to take a lot of the demand off the heaters. Also, the canister filter was turned off for about 3 hours with no oxygen feeding it, could the hot water and lack of oxygen kill the biological filtration?
The last thing I can think of is to replace the biological media again and instead of using Eheim, I could use Seachem Matrix and/or Seachem De-Nitrate media. Iíd even consider a sump with overflow, but not for awhile. Over all the tank does look good, the algae is not out of control, but some older leaves do show it and the film on the glass appears every week or so.
Iím constantly on YouTube and other sites to educate myself on anything aquarium, lately itís been canister filter maintenance. Itís very debatable whether or not the canister is a fertilizer/nitrate trap, some people say it could be, others say No. But I am willing to again remove all the biological media and replace, I think that is my next step.
Any suggestions would be great, if anyone has had a similar issue, please let me know what you did to resolve it, hopefully I have covered everything, if not, please let me know.