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Old 11-21-2005, 09:58 PM   #1
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Phosphate levels

O.K. I just got my new Hagen master test kit. These are my surprising results:

PH - 7.6
KH - 12 deg
GH - 6 deg
Phosphate - at least 5.0 ppm (looks darker than 5.0)
Calcium - 15 ppm
Fe .5 ppm

Using Chuck's calculator, I have 9 ppm CO2
I see that my ph is higher with this test kit. (a better kit than I was using)
My KH has increased from 9 degrees to 12, probably from the CC I mixed into the substrate.
My calcium seems to be ok
and my Fe seems to be ok.

I know that my Phosphates are way too high. This could probably explain the slight outbreah of algea that I see. I did a 25% water change after getting these results and added Flourish and Flourish Potassium. I did another phosphate test after the water change and it was just as high. I plan on doing at least one more 25% water change tomorrow. Any ideas how to bring phosphate levels down aside from water changes? I know that I have to lower my ph in order to increase my CO2. This may take a while with water changes. My KH is high also, but I will add some ph7.0 regulator. I don't expect it to work too well, though, because the Kh is so high. I will continue 25%water changes either once or twice a day until I see the phosphates drop down to around 1.5-2.0 ppm. Let me know if I am on the right track. I won't be adding anything except Flourish and Flourish + Potassium for the next few days. I'm hoping that the phosphates will drop to within reason in a day or so. Apparently I need to do more frequent water changes. I just don't understand why there is so much phosphate in the water if I have live plants. I thought that they would be using up most if not all of it. Any help is appreciated.

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Old 11-21-2005, 11:03 PM   #2
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Instead of using the PH Regulator which may or may not work and is likely to cause you other problems, you could mix RO water with your tap water. This will help bring down both your KH and PH, without messing up your water chemistry. Unfortunately with the CC in your gravel this may be a losing battle. Best bet would be to try to get as much of the CC out of the gravel as possible.

As far as the Phosphates, there are several possibilities. First test your tap water for Phosphates. Phosphates in your water source or overfeeding are the two most frequent reasons for high Phosphates. Phosphate consumption by your plants is limited by your Nitrate levels. If your Nitrates have bottomed out this would allow the Phosphates to grow unchecked. If the Phosphates larger amounts than the plants needed it, this would also allow it to rise.

To get your Phosphate levels down, water changes if your tap water doesn't contain Phosphates is the easiest method. If it does, you may want to try one of several phosphate removing chemicals. I know people have reported success with several of these, but don't remember which ones off hand.

As to the PH and CO2, it sounds like you've got it a bit backwards. You need to add CO2 which will result in the PH dropping in relation to the KH. If you just adjust the PH without adding CO2, your PH and KH will rise and fall together. If you do manage to change your PH without changing your KH and without injecting CO2, this means that you have replaced the buffering capabilities of your water using chemicals which results in completely invalidating the CO2 calculations.

Good Luck

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Old 11-22-2005, 11:19 AM   #3
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I am injecting CO2 into the water. I have the Natural Plant system from Nutrifin.
I also have a piece of driftwood in the tank. Originally, I added the CC to compensate for the expected drop in PH when I added the CO2. The driftwood would also tend to drop the PH, so I thought I was heading a PH crash off at the pass. I will check my tap water for phosphates and if the exist, then get a RO filter so I can still use it for water changes. As far as the PH and KH go, last time I checked they were 7.1 and 9 respectively. That was several days ago. I am now noticing green hair algea on my plants and a little green algea on my wood. I know that the phosphates are the reason for the algea. I just need to get them down. The CO2 I am injecting was enough when the PH was 7.1, but now that it is 7.6, it's not enough anymore.
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Old 11-22-2005, 12:24 PM   #4
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Adding junk like that is a great way to screw up water chemistry, spawn more algae (especially pH down products) and empty your wallet.

I still don't think you understand CO2, Kh and pH relationships, when you say "The CO2 I am injecting was enough when the PH was 7.1, but now that it is 7.6, it's not enough anymore."

That's an incorrect assessment. This is what's going on: Now that your Kh has increased due to the CC in the substrate, your pH has increased proportionally to the amount of Kh/Alkalinity you've added via the CC Now that your Kh is 12, you need to inject more CO2 because the water is 'fighting' the CO2 more now....which is exactly why you didn't need to add CC in the first place. Any Kh over 3degrees is plenty of buffering for CO2 injection.

Now that your Kh is up to 12, you need to aim for a pH of about 7.0 which gives you 36ppm of CO2...the top end of what I've found is good. Anything above that' is just wasting CO2.


As far as your test kit goes, what brand were you using before? IMO the Hagen kits aren't that great. The two I used were clumsy and less accurate than an Aquarium Pharm. kit.
For the record, I feel the SeaChem phosphate test kit is as accurate as you can get unless you wanna drop $50 on a LaMotte or Hach test kit.
Former advisor and planted tank geek...life's moved on though.
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Old 11-22-2005, 12:55 PM   #5
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The test kit is very innacurate for measuring Fe (99% of test kits cannot measure iron accurately). Never had a need to test for calcium. Most get enough from their tap. PO4 is high which would lead me to believe your tank is starved of No3. I do kind of disagree with part of the above statement about kh rising means more Co2. 30ppm co2 is 30ppm co2 no matter what the ph or Kh is. I would say your readings were off from test to test. You don't have to add more co2 to a kh of 12 vs a kh of 9 to get 30ppm. You would have to add more to lower the PH more but not to keep the same co2 levels. The nutrafin co2 system is nice for small tanks but hard to keep co2 stable for any period of time.

If your kh is 12 then if you are adding 30ppm co2 your ph should be ~ 7 already which leads to inaccurate testing or inadequate co2.

In short a kh of 12 and a ph of 7 = ~ 26ppm co2
A kh of 9 and a Ph of 6.9 is about the same.

If Co2 is constant and accurate your PH/kh testing is off. Kh testing can be innacurate if you water has a lot of non carbonic alkilinity such as borate. A problem in the southwest U.S. and apparently here in SW Ohio as per our water quality report.
For in much wisdom [is] much grief: and he that increaseth knowledge increaseth sorrow.
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Old 11-22-2005, 01:36 PM   #6
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The CO2 measurement was done with CHuck's calculator. Here is what I'm doing. I just ordered a phosphate filter from Big Al's along with Flourite for my substrate. I am going to do a substrate change to the flourite which I know the plants will like. The KH of my tap is 2. the ph is 7.0. After I get the CC out of my tank and put in an appropriate substrate, I should no longer have a problem with high phosphates. The phosphate filter will take care of that. Apparently, my tap water is at least 5 ppm for phosphate. My other measurements were all good

Fe .5
NO3 15 ppm
Gh 6
Calcium 100 mg/L

If I resume what I have been doing after I deal with the phosphate problem, all should be well. I should have listened to Malkore and not put the CC. I rushed to fix it before I finished my homework. Thanks for the help guys and I'll let you know how I make out with my substrate change.

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level, phosphate

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