How much GFO should I use for a 40 gallon tank

Discussion in 'Water Chemistry' started by bbrian189, Sep 16, 2011.

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  1. bbrian189

    bbrian189 Skunk Shrimp

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    I have been having a lot of cyano / hair algae lately. I ran y tank without a skimmer for a few months due to my cheap crap one breaking.

    I have some granular ferric oxide (GFO) BRS brand.

    How many tablespoons should I use for a 40 gallon tank with a ten gallon sump?

    I don't really know my phosphate levels because my test kit sucks.. I am just assuming that they aren't great and that using GFO could do more help than harm.

    Please let me know.

    Thanks
     
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  3. steve wright

    steve wright Super Moderator Staff Member

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    If its your 1st time using GFO
    then you are best using a ratio of 1 table spoon per each 20 gallons
    so 2 . 5 table spoons for your system

    you will need a reliable test kit, in order to know when it needs to be changed
    keep running at just 2.5 tablespoons in your system for at least 1 month

    many species of coral can react negatively to water chemistry changes, even changes designed to improve water quality
    thats why a 4 week period at half dose for tank size is suggested

    once your test kit is telling you that you have 0 phosphate, you can gradually increase to 1 table spoon per 10 gallons , thus 5 table spoons for your size set up

    Steve
     
  4. bbrian189

    bbrian189 Skunk Shrimp

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    I am not looking to do GFO permanently or anything. I was just looking to hopefully do it once or twice to get the phosphates back down.. due to me not having a skimmer for a while and possibly overfeeding.

    Can i run GFO once or twice and have it lower my phosphates?

    Or would phosguard be better for this?
     
  5. steve wright

    steve wright Super Moderator Staff Member

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    You can certainly run it periodically
    but majority of hobby grade test kits are not very accurate
    so even when the test kit indicates zero, its almost certainly not the case
    hence many of us run 24/7 as prevention rather than cure

    Phosgaurd, the Aluminun based phosphate remover, does according to many in the hobby leach what it has absorbed once exhuasted, which GFO does not do
    also some coral species are irritated by the aluminun compound, leathers and toadstool corals have been noted to withdraw polyps, shrivel and shed skin more often in set ups where Phosguard or other aluminum based phosphate removers are used
     
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  6. bbrian189

    bbrian189 Skunk Shrimp

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    So, If you think that if I just ran about 2.5 tablespoons in a filter bag twice this week (in the sump) that would reduce my phosphates to a manageable level (if they are there)?
     
  7. AZDesertRat

    AZDesertRat Giant Squid

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    Start with 1/2 the recommended dose or 1/2 of a tablespoonfull, abot 5 grams, per 10 gallons of system water. More than that and you shock the system and can bleach corals. After a week or so remove it and add the same amount again. Its best to start out slowly and work up to the full does of 10 grams or one level tablespoonfull per 10 gallons if you choose to run it continously as many of us do. Phosphates are added every time you feed so running at least a small amount is cheap insurance just as running as small dose of carbon is.
     
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  9. ermano

    ermano Zoanthid

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    I run GFO 24/7. +1 on AZ's comment about feeding. It's inevitable to get SOME...while phosphates are a major organic source for algae, trying to reduce other organics will help you out more. I don't know if you replaced your skimmer or not but that will definitely help you. (If you already have, good).
     
  10. bbrian189

    bbrian189 Skunk Shrimp

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    I've replaced my skimmer already. I'm thinking about throwing 2.5 tbsp in a filter sock for a little how long should till I wait to throw another dose in..I only have enough to do it like 3 or 4 times