Water Turn-over Marine

[Mark.C]

Hey guys,

I have just set up a 180l reef tank with 2 external filters that are rated at 860l/hr each, so that means that i currently have 1720l/hr. I wanted to get another 2 powerheads and didnt know if to go with x2 2000l/hrs or x2 3000L/hr?

If i go for the 2000's then i will have a flow rate of 5720L/hr, would this be enough or should i go for the 3000's which will give me 7720L/hr, would this be too much and blow the fish all round the tank

[CATFISH mick]

Hi Mark,

for filtration 5-6 times per hour is good. 8-10 is even better. Remember though that quoted filter turnover rates are stated with no media added, at 1m head pressure. Count on a 50% reduction once you add filter media. And a 10% reduction for each 100mm you pump over 1m head.

For circulation, more is always better, my old reef tank, which was 600lt had about 50x turnover each hour. If you have plenty of live rock then the fish will be fine. You can always adjust the outflow to better suit the tank.

[Mark.C]

Thanks Mick,

So based on the 50% power of my externals they will be turning over 860L/hr between them.

So the 2000l/hr power heads would take that up to 4860L/hr which would be 27 time water turn over
and the 3000L/hr would take it up to 6860L/hr which would be about 38 times water turn over

Im thinking that the 3000's may be the way to go based on what you said about more is better, i have 25kg live rock in a 180l tank (3 foot tank) so hopefully that will be enough?

[CATFISH mick]

I'd go the 3000's for sure. Is there much of a price difference?

[Mark.C]

Theres only £5 difference between the 2000's and the 3000's 

thanks mate, i have def going to go for the 3000's 

[arcticfox]

I'd go 3000s too

[Mark.C]

thanks guys i will be picking them up on Friday .

Another question i have is should i be using bio pearls in my filter to reduce the nitrate levels for the corals?

If i should be do i put these in to the filter once i have my protein skimmer up and running?

I was told that the rea sea protein skimmers are the best is this true?

Do i need a UV steraliser?

Sorry for the questions but i want to confirm what my LFS have said before i do anything as i got bad advice for another LFS on my other marine tank?

[CATFISH mick]

I'm more than happy to be corrected, but aren't the bio pearls designed to go into something like a fluidised bed filter? I'm not 100% familar with the product, but I assume they need to be kept in suspension, in a water vortex to be effective, so placing them in a cannister type filter, where they remain stationary could defeat the purpose, and they may not work correctly, or as stated?

If you have plenty of live rock and a deep sand bed, then this will become your 'Bio Filter' and also double as  Nitrate reduction, (Berlin Method), this leaves the filters under the tank to be used solely for mechanical filtration (Filter Floss) This will need to be cleaned on a rotational  basis, twice weely, do 1 on Sunday, the other Wednesday/Thursday.

UV? Debatable if you need one or not. If your using RO for water changes, then that water will be 'Sterile'. If you Q/T all new additions, including rock and coral, then pathogens will be minimal. For a small 3ft tank, I thinl I'd risk it and do without one. A super 'High Tech' 'Hi Spec' very large cutting edge reef tank with very expensive and sensitive livestock, the addition of a UV would be a no brainer.

[Mark.C]

Im sure you are correct but i was told that if i put them in one of the trays of my filters then they would have lots of water movement flowing past them and they will be moving around due to this flow?

Im sure i am incorrect/misinformed but i thought that the bacteria that was in the lice rock ect would only convert amm and nitrite and that nitrate had to be removed through water changes?

That was my understanding of the UV. I only ever put Ro in the tank and do water change every week so i think i will risk it as you have mentioned

[CATFISH mick]

Im sure you are correct but i was told that if i put them in one of the trays of my filters then they would have lots of water movement flowing past them and they will be moving around due to this flow?

Im sure i am incorrect/misinformed but i thought that the bacteria that was in the lice rock ect would only convert amm and nitrite and that nitrate had to be removed through water changes?

That was my understanding of the UV. I only ever put Ro in the tank and do water change every week so i think i will risk it as you have mentioned

Hi Mark,

The bio pearls are quite small, so you may have to put them in a fine filter sock. I've done some reading and it seems that you can use them in a cannister filter, well others have anyway, and had good results with Nitrate reduction and phosphate reduction. maybe well worth a try, especially if your struggling with Nitrate, or phosphate, both of which can be an issue in new marine tanks.

Your correct. Bacteria present in live rock and sand do convert amm to Nitrite and nitrate, but in marine tanks there are other bacteria that will convert nitrate into nitrogen gas, hence fully completing the nitrogen cycle. Water changes are still a very good thing to do, and you should keep doing them, especially since the tank is new. In time though the populatios of denitrifing bacteria will grow in numbers, helping you keep on top of nitrate.

[Mark.C]

Thank you for your reply, very informative as always.

Yeah I was thinking about putting them in a filter bag and replacing one of the pads. I think I will replace the carbon with it as I have 2 filters running and the other will still have the carbon in that one.

I’m not even sure if I am going to need them as I use Ro and I drain my frozen food before putting it in the tank so I don’t think that I should have much phosphate in the tank? And I will be doing water changes every week, although as you said it is a very new tank and the nitrates might be higher.

Thank you for the information with regards to the nitrate bacteria, I didn’t know that. So I guess that the nitrogen gas is then exchanged with the ambient air at the water surface and out of the tank?

[CATFISH mick]

Thank you for the information with regards to the nitrate bacteria, I didn’t know that. So I guess that the nitrogen gas is then exchanged with the ambient air at the water surface and out of the tank?

My Pleasure.

You are correct. Converts to harmless nitrogen gas, escapes out into the room.

[arcticfox]

Good info from Mick as per. For a eg when I set up my 4th I had nitrA and phos in tank as tank matured and ran rowaphos both reduced and were always 0. New 6th set up now and no prob with Po4 but getting nitrA :-(. Tank should sort once it matures more and water changes take affect