Cannister & Nitrates

Discussion in 'General Discussions and Advice' started by sandlewood, 24 Mar 2010.

  1. sandlewood

    sandlewood

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    Dear Hennie

    I have read a comment you made somewhere else on the forum about cannister filters and nitrates and need some advice.
    I have an eheim cannister filter running in line working as a phosphate reactor. I have phosphate remover and carbon in two baskets and some of the original eheim "gravel" filter media in the botto basket with the usual floss and nylon pads covering the first and third baskets.
    I have noticed a slow build up of nitrates lately and am wondering if this cannister could be the cause?
    My tank is 480 l with a 150l sump with skimmer DSB (50cm x 30cm).

    Perhaps I should remove the "gravel" and sponges and just leave the carbon and phosphate remover in the baskets?

    I would appreciate your comments.
     
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  3. butcherman

    butcherman Moderator MASA Contributor

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    how often do you clean the canister filter out? what other forms of filtering are you running?
     
  4. sandlewood

    sandlewood Thread Starter

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    Hi - Skimmer in sump, a 30 x 50cm DSB and an algae scrubber approx 25 x 20 cm square gauze. I also have a few pieces of live rock in one compartment of my sump. Main tank had about 60kg live rock and a shallow substrate (3cm) of crushed coral and aragonite mixed. Tank has been running for 15 months.
     
  5. butcherman

    butcherman Moderator MASA Contributor

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    how often do you clean the canister out
     
  6. RiaanP

    RiaanP Moderator

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    DSB, too small for me. I prefer it as big as possible.

    Algae scrubber, if double sided should be ok. Depends on your growth rate. Do you clean it weekly?

    crushed coral parts in substrate, that part I do not like. But I do not know how it will function is mixed with aragonite.

    Maybe post us a picture of your sump, so we can see what you got.
     
  7. sandlewood

    sandlewood Thread Starter

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  8. sandlewood

    sandlewood Thread Starter

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    The dsb is also in the third compartment just before the return pumps.
     
  9. RiaanP

    RiaanP Moderator

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    I will make the compartment with the LR also another DSB chamber. The DSB you have is too short, nothing can get time to settle. Only way is your slow must be really slow.
    And use playsand at 15cm deep.
    Can suspend or put a piece of eggcrate on old DSB and put that LR pieces there.
     
  10. sandlewood

    sandlewood Thread Starter

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    So you dont think the cannister is a problem? I thought about building a remote DSB over the sump using a plastic tub approx 75 x 40 cm in addition to what I have here.
    How often should you clean the scrubber? I have been reluctant to clean this to thoroughly for fear of taking off all the "good stuff". Perhaps I should clean one side at a time.
     
  11. RiaanP

    RiaanP Moderator

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    Scrubber, first time you clean it is after two weeks, thereafter its a weekly job. Well for me.
     
  12. Reef Maniac

    Reef Maniac MASA Contributor

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    Yes, I think that the cannister filter is at least part of your problem. This is further complicated by the fact that you only clean the filter once per month.

    Agreed - remove one of the sponges with your next cleaning (or ASAP), then allow the system to regain equilibrium for (say) two weeks, then remove the next sponge, repeat the equilibration period, and then remove the ceramic noodles.

    Agree with Riaan here :thumbup:

    Hennie
     
  13. Nemos Janitor

    Nemos Janitor

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    Also if the carbon is saturated to could also just be surface area for aerobic bacteria.
     
  14. sandlewood

    sandlewood Thread Starter

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    Thanks for the advice. How often should one replenish the carbon?
     
  15. sandlewood

    sandlewood Thread Starter

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    Also. assuming that the ceramics and sponges are removed, is there any reason why one can't use the cannister as a reactor?
     
  16. Nemos Janitor

    Nemos Janitor

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    There is not a definite answer to that i am afraid. It all depends on the GAC make. amount, DOC load etc. So it could last 4 weeks or 6-7 months. The best indicator is the colour of the water. If it starts to yellow the GAC is kaput and needs to be replaced.
     
  17. Reef Maniac

    Reef Maniac MASA Contributor

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    Just be aware that most (all ???) activated carbons release phosphates into the water, and the longer they are in the system, the more phosphate they release... Carbons also tend to saturate rapidly, removing most of what they remove within the first few days, thereafter they just become another aerobic substrate, and worse, they can actually release what they have removed if left in the system for too long.

    I would recommend only running carbon intermittently, say one week out of every 3 or 4 weeks.

    Hennie
     
  18. sandlewood

    sandlewood Thread Starter

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    In that case, can you just run carbon in a bag in the sump? This would make it a lot easier to get at if I am going to remove it after a week.
     
  19. Megalodon

    Megalodon

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    Ok, DSB as others have said should fill as much of the compartments as possible.... IMHO a small DSB is almost worse than useless as it can become too saturated with organics and become a nutrient sink rather than a processor.

    The ATS.... you have decent globes it seems but they need to be focused more directly on the screen - ie lower and perpendicular to the screen, and closer to it... then even with the canister you shouldn't see high nitrates.

    However, seriously, a canister is worth more harm than good on a reeftank...unless it is run intermittently with phosphate remover/ zeolite etc.
     
  20. Reef Maniac

    Reef Maniac MASA Contributor

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    Unfortunately, no. Carbon only works well if water flows through it, and not just around it. What I do is to have the skimmer discharge (i.e. very clean water) run through a leg of a nylon pantyhose and then into an old square plastic container housing the "foot" of the pantyhose. The bottom of this container is drilled with lots of large holes, allowing for unrestricted through-flow. a largish diameter PVC pipe (say 100mm diameter) would also work very well for this (and you won't even need to drill the bottom...). I also place my phosphate remover in this "reactor".

    HTH :)

    Hennie
     
  21. Nemos Janitor

    Nemos Janitor

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    Hennie two little fishes have a product called Hydrocarbon 2. They make all sorts of claims. Now i did a google on hydrocarbon and got a chemistry lesson i am sure to flunk. If you know please help out in an explanation between normal GAC and Hydrocarbon.
     
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