need a little help

[mwatson]

I have stumped my local guru, and I have stumped myself ( 10 yrs exp) and I have stumped all but a few local friends with the exception of one possible idea.
I have had four tanks over the last 10 years, I have had all the usual problems, but with luck and lots of experiance been ok, but heres my problem.
I set up a 55 gallon tank in Feb ( about mid month) I place 60 pounds of established live rock, a little from each tank. I added some new substrate and added a bag of live sand for a little help. I am running the usual under gavel filterbed with power head and an external filter that is also part protein skimmer and has a seperate area for bio, which I filled with bio balls from another tank. I started this tank by placing a large uncooked shrip from my local fish market and let it sit 2x weeks making the Ammonia, No2 and No3 skyrocket..no big deal, I waited for the numbers to come down ( which happened very quickly).

when the numbers looked good I did a %50 water change, added 2 small crabs and 3 little cleaner clams and waited for the numbers to rise a little and was going to add some fish. My ammonia stayed at 0. My No2 came up a little .25..maybe .50 for a day no big deal, No3 went up to 40ppm. I waited the numbers went down like they should..with the exception of No3...it stayed at . 40 ppm..and hovered..never went down. I kept the crabs and clams in and just maintained the numbers Ammonia went to 0 No2 went to 0, No3 stayed at 40ppm. I did a %30 water change 2x days ago thinking the level would drop, the No3 dropped to 20ppm, one day later its going up I would say to 30ppm. I have no idea why it didnt go down more and even less idea why its headed up so fast. Ammonia and No2 are still 0! and have never gone up!
My guru and all my friends but one are stumped, only one idea was that since a large number of bacteria were introduced with the established LR and LS and bio balls that they were not challenged enough and now the small crabs and clams are really not making a large amount of wastes and thats why my ammonia and No2 has really never gone up, the solution is go get some small starter fish and let the ammonia and no2 go up again and see what happens.
Does anybody now how to solve the Ammonia(0) converted to No2(0) can be converted to No3 at 20 to 30ppm?????

 

[mr_x]

maybe your never going to see a "full cycle" due to the established rock.
i don't think you needed to put a shrimp in the water, because you had plenty of bacteria on the LR aready. you were trying to cycle a tank as if you didn't have any live rock.
why did you decide to go with bio balls and an undergravel filter?
those are things of the past! i think the undergravel filter was a mistake. the bio balls aren't needed due to the live rock....60 pounds being enough to hold the necessary bacteria to sustain a 55, with a reasonable bio load.

 

[scopus tang]

What are you using as a substrate over your undergravel filter and where did it come from? How deep is it? Did you clean the bioballs or simply move them over? disturbed bioballs are often themselves a source of nitrates, as the balls themselves produce nitrates, but do not break them down. However, your established live rock should have been able to counter that. Nitrates have to come from the nitrogen cycle, unless you are overfeeding with some type of food that is high in nitrates. If you have a lot of nitrates leaching from disturbing an established system it can take awhile and a number of water changes to bring nitrate levels down. I would say to continue doing water changes, but monitor your feeding (if you are). Eventually your nitrate levels will come down, they have to, so long as nothing is feeding the cycle.