External canister filter vs Live Rock to remove Nitrates

[mling]

I’ve been advised, by a LFS staff member, to buy an External Canister filter ( Eheim 2215 ) for my 45G tank because my 45 pounds of live rock together with a protein skimmer is insufficient. That the live rock will not remove Nitrates and I need an external filter to do that. It was either the $145 external canister or I fill up my tank with more live rock. He than suggested that I would need at least another 40 pounds of cured live rock to make up for the lack of the external filter.

Is it true that you need an external filter to remove Nitrates or is this a sales pitch to make a $145 sale ?

My Nitrate level has been under 10 N mg.l since it finished it’s cycle about 2 months ago. I have a ViaAqua Multi-skimmer which has a built in filter. Is this filter enough for an external filter ?

[Phishnoob]

I think that there are going to be a lot of folks that disagree with that advice here on the filter for use in a salt water tank. The only thing that I have seen them mentioned as good for is some mechanical filtration with floss and carbon now and then to polish the tank.

Buying an Eheim like that was one of my biggest mistakes and putting in the stuff that looks like dog food was another. It is a detritrus trap. I tossed mine and just stick a bag of floss in the sump now.

One of the super pros will chime in I am sure on the Nitrate thing but you have a higher ratio of rock to tank size then I do and it is just fine.

We use the multi-skimmer on Mrs. Phish's tank with no medium but the carbon backed pad and have the UV bulb and it stays gorgeous in there. That is pure mechanical filtration and we change out the pad pretty regularly.

Good luck with your tank!!!

Phishnoob

[kwjones]

The LFS is trying to sell you something.

Think about what a canister filter does. I traps detritus. What happens to detritus if you leave it in the canister filter? I rots and eventually turns into nitrates. Canister filters are not evil or bad, but most people don't clean them often enough and they end up turning into a nitrate factory.

A canister filter can be a great cleaning tool. If you decide to get one, don't install it permanently in your tank. When you're cleaning, blow the detritus off your rocks and then hook up the canister filter for a few hours to suck everything out of the water. Disconnect the filter, clean it and store it for the next use. You don't have to buy the expensive filter media either, just go to a fabric supply store and get the polyester fiber fill. Use it a couple of times and rinse well and let dry between uses.

Phish...should have hung onto the canister...makes vacuuming the tank easy.

Good luck with the tank!

Kevin

[Phishnoob]

I just tie the mesh bag of floss with a carbon bag inside it over the tank return piece of tubing. All of the tank flow goes through it and although not as tidy it does the job. The canister filter broke fourth time I opened it for some reason and I could not justify spending more money. It is amazing how yucky the floss gets, even with a giant old skimmer running.

If I still had it that might be better to use, but the floss in a bag trick cost me six bucks.

Phishnoob

[Geoff]

you should have plenty of LR for that tank. unless you just want more for the looks.

they are trying to sell you something.

G~

[Jimbo]

45lbs of live rock should be more than enough, especially if it's the light stuff (tonga, marshal island). Live rock provides denitrification ( changing nitrate into nitrogen bubbles) something a canister filter dosn't normally do.

I like my canister filter for use with carbon and phosphate remover. But still need to clean it weekly, biweekly. This also facilitates a small partial water change, since it holds a couple of gallons of water.

[bent240LV]

yeah in my fowlr tank im going to have about 60lbs of live rock thats 1lb per gallon. and i also am goign to use bio balls in my sump, i know that everyone says not to but ill give it a try, most all fowlr tanks i see have bio balls so it cant be that bad.

[OodleyBoodely]

The liverock will provide the best possible nitrate reduction, naturally. If the lfs was telling you you had to have the canister for 'nitrate reduction', then their hope was to sell you the filter and get you using a nitrate resin on a regular basis (very expensive). Either that or they don't know what they are talking about.

The trick to getting full filtration safely from the live rock is 1. to have enough lr (you do), 2. allow enough time to cure (even so-called cured will usually have some die-off and will cycle again in your tank), and 3. stock the biomass in your tank very slowly (to allow the bacteria time to increase to be able to control the new waste load).

[OodleyBoodely]

Bent24,
The bioballs are often used on FO and FOWLR systems to increase the biological filtering since the bioload is often too much for just the small amount of rock (if any) that is used. The bioball, however, will not control nitrates and in fact will create nitrate that will have to be removed from the system in some other manner (water changes, algae harvesting, resins).

[Tasher80]

I have a 72 Gallon Bow Front tank with 75 Pounds of live rock, I have a sump with a skimmer in it and thats all for filtration. I run filter floss just to catch debris. I run a HOT Magnum canister filter whenever I blow off the rocks of I see stuff in the water then the filter sits in the closet until next use.

[theduker25]

OK, I have a FOWLR 29 gal with a small grouper, small dwarf lion and a hawkfish and about 35-40 lbs of LR and 2 inches crushed coral SB. Is that enough LR to keep nitrates from building up from these 3 heavy producers or do I need to reinstall my biowheels? I know oodleyboodley already schooled me on this one, but I want to clarify these general rules of thumb (LR + skimmer as only filtration) for a fish only tank with three semi-heavy eaters. I usually feed these guys 3 -4 times a week about 5-6 live minnows.

[Bleeg]

scratch the canister.. they're pretty useless and can hurt more than they help. basically, only thing good about them is that you can use them to polish your water with carbon and some phosphate filtration every once in a while.

[kwjones]

The way you clean your tank will help with nitrates more than LR or a canister filter combined. The faster you can get the stuff out of the water the less nitrates you will have.

[tdwyatt]

Originally posted by mling
I’ve been advised by a LFS staff member to buy an External Canister filter ( Eheim 2215 ) for my 45G tank ... ...It was either the $145 external canister or I fill up my tank with more live rock...

Get another LFS.

You have sufficient rock. Have you tested your water for nitrates? Although I would not be opposed to having a fresh bacth of LR in the tank, it would be because I like a lot of rock (for the critters in it), and I will buy about 45 lbs every year or so for the potential new stuff in it, not for the filtration or any specific need.

Curious, was there some issue that precipitated the comment from the LFS, or did he/she suggest this as part of the discussion of your setup?