How to estimate CO2 with high phosphates? Question

Discussion in 'Aquarium Plants' started by catsma_97504, Apr 12, 2010.

  1. catsma_97504Fishlore LegendMember

    When a tank has high phosphates (> 10 PPM), how can you determine how much CO2 is in your tank? All the charts I've see specifically indicate they are not accurate with phosphates. My tank run 4-6 KH and the ph runs 6.4 - 6.8 with a DIY CO2 system. Thank you for helping me figure out how to determine if I have enough CO2.

    I've been fighting GW for a few months now, but it does appear to be clearing up a little bit with the uv sterilizer I recently purchased and the months of phosphate removal products.
  2. ryanrModeratorModerator Member

    You can buy CO2 test kits, they're a little expensive (around $30AUD), but they specifically measure CO2.  

    Nutter or Nate will probably pipe in here, as they are better educated in this area. The other info they may want is Nitrate levels

  3. pepetjWell Known MemberMember

    Any idea why your phosphates are so high? You may be overfeeding your tank.

    Look, there is an indirect way to know if your DIY CO2 is way overboard or not. Compare the pH reading of your tank before and after CO2. If the variation remains within a full 1.0 it should be safe (e.g. w/o CO2 it's 7.4; w CO2 it's 6.7). If it is greater than that (e.g. w/o CO2 7.7; w CO2 6.4) be careful: your fish may pay the price (unfortunately it happened to me).

    You could get (or even better build your own DIY) a drop checker but keep in mind that even the best built has an standard error of measurement of up to 36%. Despite that, it's quite useful for our purposes.

    Another way is to just set a floor for KH. Say you feel safe with 2.5 dKH. Eventually your tank may go to 2.0 or even 1.5 dKH. When that happens, partial water changes (small yet frequent is safer than a big one) will solve that.

    I have a Hach CO2 test kit. I paid a bit over USD100 for it. CO2 regeants must be stored at 10-25C (50-77F); if that is not observed you will end up with grossly wrong readings. I figure that's the reason CO2 tests are not manufactured for the hobby: a bit too warm or too cold and its damaged for good.

    Santo Domingo

  4. catsma_97504Fishlore LegendMember

    Yesterday's test results were:
    0 ammonia
    0 nitrite
    0 nitrate (I know, but it has been like this ever since the GW started)
    6 kH
    4 GH
    6.4 pH
    >10 PPM phosphate -- although the API test color has gone from nearly black to a dark blue, so it is coming down. This test is so high that the glass tube is permanently stained!

    I also have:
    T5HO Lights on 8 hours
    DIY CO2 with 6 2-liter bottles. Am averaging a bubble 1-2 seconds
    UV Sterilizer running over the weekend, but the pump is weak. Waiting for replacement shipment.
    Been adding Flourish Complete, if that makes a difference.

    Well, that's about all I can think of tonight. Let me know if I left something out.


  5. catsma_97504Fishlore LegendMember

    Yes, this tank sat with little to no maintenance last fall when my water pump went out.

    I am not overfeeding as everyone assumes.
  6. mathasWell Known MemberMember

    The problem with these ideas is that grossly elevated phosphate levels can invalidate commercial test kits and drop checkers, as well as the simple pH/KH/CO2 chart.

  7. NutterFishlore VIPMember

    As far as I know with high phosphates there isn't a way to accurately measure how much co2 is present. I know that any phosphates throws out the KH/PH charts & is a big part of the reason I don't trust them at all. I'm also pretty sure that the phosphates can throw out the accuracy of commercial testers as well, just like Mathas has stated. Drop checkers don't really give an accurate assessment of how much co2 there is even when there are no phosphates & the liquid test kits can be unreliable at the best of times to. The best one I have come across is from Vita-Kraft but it isn't commonly available & it won't read accurately when there are phosphates present either. I simply judge how much co2 is present by looking at my bubble counter. So long as I see enough co2 going into the tank & I know it is being diffused effectively, I don't bother worrying about exactly how much is actually present.
  8. Nate McFinWell Known MemberMember

    A drop checker using a 4dkh reference solution is the best IMO. It wont give you exact #s but it will give the general zone to be in that your fish will tolerate. 30 ppm shows up as a nice green color, too much and it goes yellow, not enough and its blue.
    Your tank water is a non factor in a drop checker as well.
  9. catsma_97504Fishlore LegendMember

    Ok, I get that I'm pretty much SOL with this one. I'm using phosphate removers so should get this number in balance.....eventually. I guess my next question should do I know when I've attempted to add enough CO2? The bubble counter I set up shows that I'm getting an average of one bubble every 1-2 seconds. I've seen in other posts where someone is getting 3-6 bubbles per second. Is there a balance here that I should be aiming for? Or, is my plant growth, or lack thereof, the indicator I should use?

    Once the GW is gone, I want to turn my focus back to adding plants to the aquarium and I want to have healthy plants. My Ozelot has dropped almost all its leaves and looks like it may die (hard to see it clearly for the GW tho); one of the two Amazon Swords is producing baby plantlets; the Cryptoryne (sp?) is growing like a weed; Anubias is doing well, I think, because I've been noticing the underside of the leaves covered in bubbles (I know they are slow growers, but haven't lost leaves). Oh, and let's not forget the Banana plant that had a 20 inch stem with leaves floating on the surface (since died off).

    Please excuse my ignorance, but this is my first attempt to include live plants in my tank and this balance is new to me. I'm trying to understand it. I have great success growing garden/flowering plants, so it is frustrating that the aquarium plants are another issue.
  10. catsma_97504Fishlore LegendMember

    I'll have to check this out further. Wonder if I can DIY or find something locally.

    Thanks Nate and Nutter for all your information.
  11. Nate McFinWell Known MemberMember

    I bought this one and have been very happy. It comes with the 4dkh solution. You can make your own with baking soda and bottled water but this was a little less time consuming. LOL
    If you ever buy a pressurized system or dry ferts Orlando, the owner, is very eager to answer questions and is VERY knowledgeable about planted tanks.
  12. NutterFishlore VIPMember

    Hard to say exactly what is a good bubble production rate for a given tank. It really depends on how efficiently the co2 is being diffused. Assuming 100% diffusion is being achieved & that this is for your 90gal tank, then I would be aiming for 5-6 bubbles per second. If your not achieving 100% diffusion then you may need even more. For 90gal you will be better served by investing in a pressurised co2 injection unit than relying on diy co2. If you do want to run diy co2 then I think you are going to need to be running at least 4 yeast generators & 6 would be better.
  13. catsma_97504Fishlore LegendMember

    Yes, I'm trying to set up my 90 gallon to include plants. And, I do realize that I should have a CO2 injection system, but money is my issue. I've well over spent buying the new light and canister filter, plus the unexpected expense to deal with all the algae. I didn't realize that T5HO lights also meant CO2 was required. So, I'm trying to manage with the DIY CO2 until I can come up with the money.

    Currently, I have 6 bottles running, but our weather has also been unusually cool. I think I'll up the yeast to 1 tsp per bottle to get it going better. I realize this means more attention....but I'm a baker so yeast and sugar are plentiful in my house. I can get sugar at 23 cents a pound and have lots of yeast in my freezer.

    I have the CO2 going into my filter's intake. Don't know how efficiently it is being diffused, but it is all I can afford with a single income and teenagers.

    Nate - Thanks for the link. I'll check it out.

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