nitrate levels

[karenscritters]

I have a 240 gallon glass swim tank, that is drilled with 1 inch holes, uses 1/2 inch PVC thru the bulk heads, has UG filter with crushed coral over that, live rock, 2 nu-clear canister filters, a hang on protien skimmer, and a UV sterilizer. I've done any where from 25%-90% water changes and can't seem to get my nitrates under 20-40. Other than a fist sized Stars and stripes puffer, lg sail fin tang, and lg blue tang, there are 6 small-med wrasses, or similar fish. Fish are fed daily with flakes, pellets or frozen, but only enough that gets cleaned up in less than a minute. I realize I'm limited due to filtration method and size of pre-drilled holes, but there really isn't a logical or easy way to change that, so sumps and overflows can't be added to this tank. Any suggestions on getting nitrates down in this system?

I guess my question would be whether the UG filter with 3-4 inches of crushed coral over it is causing my nitrate problems. I was under the assumption that this becomes the biological filter and should be helping reduce nitrates. This tank has been up and running for 27 years!

Also, the nu-clear canisters do not leak with the pump not running, but the pumps are sucking minute amounts of air thru them and filling the tank with TINY bubbles. Do the cartridges also act as biological filters, or just remove dietrus? As they get dirty, more bubbles are produced and the tubing starts collapsing. I have been changing and cleaning the cartirdges weekly, so not sure how much biological filtration they provide.

Hobby Experience: 40 yrs, swim only tanks and UG filters

 

[Poorcollegereef]

hum, I guess your nitrates may be a result of serveral factors. Yes the UG filter and crushed coral may be a nitrate trap. In addition, the canister filters can collect detritus and become a nitrate trap as well. Both could be contributing factors. I think that a tank that is 27 years old (wow, older than I am) may have accumulated significant organic matter in the substrate. I would bet on the substrate

But, (just an idea) if large frequent water changes do not help, then I would check the source of you water. If you water is contaminated with higher nitrates then when top-off are added and water changes are performed, they just add more nitrates. Hope this helps

 

[miwoodar]

Are you actually *running* the UG or is it being used as a plenum ala Juebert?

20-40 isn't too bad. Don't break your back doing water changes though. Yes, do them, just don't kill yourself thinking that they are the only way. Sometimes they aren't no matter how hard you try. Here are some easier ways...

Have you ever read this thread...?
http://www.reefcentral.com/forums/showthread.php?s=&threadid=288714

Or this one...it might be a great solution for an older system...?
http://www.ultimatereef.net/forums/showthread.php?t=211460&highlight=nitrate

These solutions would be relatively simple to implement in the short term. It will be very interesting to see them scaled back to a 'maintenance' dose (assuming some form of cyclical dosing would be required of course, it might not be).

Here's another good option....
http://reefcentral.com/forums/showthread.php?s=&threadid=595109&perpage=25&pagenumber=1

 

[EnderG60]

yeah 20-40 is fine for a fish tank...but...

Ditch the UG filter, ditch the crushed coral, ditch the canisters and put on a sump. The UG, crushed coral and canisters all accumulate detritus, and if used need to be cleaned every 6 months.

you dont NEED large holes for a sump, and you dont NEED major turnover either. If you have one 1" drain and one 3/4" return you can do about 700gph of flow through the sump, which if you have a few power heads and a good skimmer.

If that doesnt drop your nitrates by at least 20 then just slap a sulphur denitrator on there and call it a day. If its just a fish only tank its not a big deal. Most of the FO tanks I setup for clients are run off a large live rock fuge, big skimmer and a denitrator. Low turnover but lots of flow in the tank and it works great.