Phosphate level problem - The Planted Tank Forum
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post #1 of 6 (permalink) Old 02-01-2006, 03:13 AM Thread Starter
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Question Phosphate level problem

I've been using a Seachem Phopshate test over the last week to test for the phosphate level of my 6g Nanocube, and it's reportedly at 3 mg/L! About 3 weeks ago, I was adding a tiny, tiny amount of phosphate to bring it to 1 mg/L. However, I neglected to test the tank shortly thereafter and after 3 weeks (and 3 water changes - 1 per Sunday), the Phosphate level is STILL 3 mg/L!

What is the deal here? I would think that 3 50% water changes over the period of 3 weeks would have lowered it? I haven't added any in that same time frame.

Any ideas!?

I suppose my main reason for posting is my quickly growing green "somewhat fuzz-like" algae growing on the glass. It's not green spot algae - I can use a paper towel and rub it off without any problem. Lighting is 18w PC (single tube fixture) - with Excel dosage at a little above bottle recommendations.

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post #2 of 6 (permalink) Old 02-01-2006, 07:29 AM
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Originally Posted by 99RedSi
and it's reportedly at 3 mg/L!
First don't always believe the test kit. If you have the potassium phosphate for dosing PO4 then just make up several calibration solutions and check the accuracy of the kit.

If that's ok, what's in the tank, are you feeding fish heavily and some brands of food will add more phosphate than others or has the water changed you're adding to the tank. If it's tap water what is the phosphate reading out of the tap? I know mine is between 3-4ppm

Hope that helps
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post #3 of 6 (permalink) Old 02-08-2006, 02:21 PM
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I once had the same problem. I tried everything imaginable to lower the levels and nothing worked until I (temporarily) used Hagen Green X. If all else fails for you then try inserting this phosphate pillow into your filter for a while.

It's a crude measure but it worked for me, and I've never had to use it again.
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post #4 of 6 (permalink) Old 02-08-2006, 05:17 PM
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3 ppm phosphate is not likely to be harmful. So, just accept that your tap water may have that much phosphate in it, and enjoy the free fertilizer. Algae are not caused by excess phosphate.

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post #5 of 6 (permalink) Old 02-08-2006, 05:39 PM
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Hoppy is right. Usually algae is caused by imbalance, or unavailabilty of a fert, not "too much" of PO4. I have 2ppm coming out of my tap and I dose 1ppm every other algae.
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post #6 of 6 (permalink) Old 02-09-2006, 05:04 AM
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Reference Sample

I thought the Seachem Test Kits came with a reference sample that you can test the kit against?

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