High Nitrates = Coral Deaths?

[rcp_pd]

Well the title pretty much says it all. Have been in an ongoing battle with nitrates latley. All other levels (see below) are fine. 55 gallon 4 year established tank with dsb, water flow is about 35x turnover, 120 lbs live rock coverer in coraline, lights are 2 150watt halides on for 12 hours a day, bioload is light, 10 gallon sump/refugium with cheato, drip kalk w/top off water, etc. Nitrates are 100+ (off the chart, so maybe more) and have been tested by 2 lfs as well as my own test. As a result I have had several colonies of zoo's, polyps, mushrooms, ricordea, gsp survive for about 1-2 month bfore they dissolve. Still have one toadstool that is doing quite well - cant figure that one out. Thoughts? Ideas? Comments? All are welcome...
Sal - 1.025
Cal - 420
Alk - 10 dkh
Amm - 0
Trite - 0
ph - 7.8 - 8.2
temp - 79-81

 

[teen]

id say its the nitrates.
4 year old deep sand bed is where i think youre getting the nitrates from. its probably so "full" its past its useful life.

 

[rcp_pd]

any thoughts on how to lower it? i am doing 15% water changes a week to keep it under control...but its not really helping to lower it.

 

[teen]

if i was you and i narrowed it down to the DSB, i would replace the sand bed.
move fish, water, coral, rock to rubbermiad containers.
dispose of the sand in the tank. rinse out the tank.
add a new sand bed. it doesnt have to all be live. you can do all regular sand and add a cup full of live sand. or just all regular sand and let the live rock seed the new sand.

 

[rcp_pd]

yuck. that does not sound fun at all. wonder if it would just be better to replace half of the old sand and add a denitrifier...they seem to be gaining popularity these days. dont really feel like tearing up the tank and the corals that i do have left and re-aquscaping....

 

[teen]

well the sand bed is a major part of the biological filtration in a tank. if its full, its not filtering any more. adding a denitrifier may bring down your nitrates, but your loosing out on the biological filtration of a sand bed.

 

[rcp_pd]

good point. looks like i may have to bite the bullet and just empty it all out. oh well...wasnt quite in the mood for an all day project but you gotta do what you gotta do. thanks for the help.

 

[miaheatlvr]

you could try syphoning it also,,i do and you should see how yucky the water i throw out is.. all nitrates and detrius.