Phosphate question

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Mike1971

Junior Poster
Apr 19, 2010
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Can someone please explain a large spike in phosphate levels in my tank and offer advice. I have had my 29 gal (first planted tank) set up for about 5 months. I am using a fluval 305, and two extra power heads and have really good water circulation. Two 24W T-5 HO light 8 hours a day. I had a red sea co2 setup, but am now using my new regulator that I built for a few weeks ago. CO2 is monitored with a drop checker that I move around, and stays lime green/yellowish. I have been doing EI dosing for about a month with incredible results. I have not had many algae issues at all, but have had issues with a couple of plants. My cardinalis and crypt parvas have not been doing well and always have some blackish film around the edges of the leaves that I cant wipe off by hand (definately not BBA, I beat that guy in my 20 before I added CO2). They also seem stunted. I have dipped them twice, once in peroxide, once in Excell/water twice over the past two months but the problem only goes away a short time and returns. I decided that I had a minor BGA problem and increased the water flow to that area of the tank. The problem stopped getting worse but didn't go away. I decided that since I do water changes but no gravel vacuming because the tank is to heavily planted that I would use Maracyn (I know silver bullet>
 
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Left C

Lifetime Members
Sep 26, 2005
2,500
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Burlington, NC
Hi Mike

A 1/16 tsp of KH2PO4 is about an 2.6 ppm addition in your aquarium (~25g of water). I'd question the test kit and/or the mulm amount.

The phosphate test kits that I've used were hard to tell what it's measurement really was. The cast of the blue color of the test sample was different than that of the color card. One was a 'red cast' blue and the other one was a 'green cast' blue. I can't remember now which was what, but they were bad. I don't know if you can calibrate your test kit or not, but if you can, There is a sticky on how to do it. The final version is the easiest. Hoppy has one at TPT too.
http://www.barrreport.com/showthrea...lutions(repost-from-Left-C)?p=42494#post42494

If the test kit is close to being right, many people report somewhat "high" PO4 levels without problems. Maybe it works for you too.

Left C
 
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Oreo

Guru Class Expert
May 6, 2010
251
0
16
Are you on municipal water? 1.5ppm PO4 is typical for tap water but I can see them using more then that in certain circumstances. If for some reason the local water plant put out a spike of PO4 in the water that could contribute to your issues.
 
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Mike1971

Junior Poster
Apr 19, 2010
22
0
1
Thanks for the replies everyone. I rushed to make that post yesterday, and 24 hours later I figured out the problem. First mistake I made is the high end of my test card is 5-10 ppm not 10-20, I just freaked out when the color went straight to dark green and misread it, and posted as fast as I could in panic. I tested my tap water and 10 gal shrimp tank (that I don't dose, just lots of moss in that tank) and Phosphates are .25ppm or less. I tested my 20 gal that I also dose by EI and got the same high reading that I did on my 29gal. So I am dosing too much Phosphate, or made a mistake not paying attention and used the wrong scoop. This morning I took my time to try and get the most accurate reading I can with my test kit and would say 20 gal is at 5ppm and 29 is at 7ppm. I am going to buy a scale that measures grams at walmart today and make a reference solution to be sure. Thanks for the replies, I guess I freaked out because I still fear phosphates. The good news is that my plants and fish are great, and this really gives me even more confidence that Phosphates don't cause algae. Thanks.
 
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Oreo

Guru Class Expert
May 6, 2010
251
0
16
Don't bet the farm on that scale without putting a check-weight on it first. Coins can be used in a pinch 'cause they're fairly consistent. You'll have to look up what nickels & quarters weigh though. I don't remember off the top of my head.
 
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hbosman

Guru Class Expert
Oct 22, 2008
277
1
18
Leesburg VA USA
Mike1971;51963 said:
Thanks for the replies everyone. I rushed to make that post yesterday, and 24 hours later I figured out the problem. First mistake I made is the high end of my test card is 5-10 ppm not 10-20, I just freaked out when the color went straight to dark green and misread it, and posted as fast as I could in panic. I tested my tap water and 10 gal shrimp tank (that I don't dose, just lots of moss in that tank) and Phosphates are .25ppm or less. I tested my 20 gal that I also dose by EI and got the same high reading that I did on my 29gal. So I am dosing too much Phosphate, or made a mistake not paying attention and used the wrong scoop. This morning I took my time to try and get the most accurate reading I can with my test kit and would say 20 gal is at 5ppm and 29 is at 7ppm. I am going to buy a scale that measures grams at walmart today and make a reference solution to be sure. Thanks for the replies, I guess I freaked out because I still fear phosphates. The good news is that my plants and fish are great, and this really gives me even more confidence that Phosphates don't cause algae. Thanks.
Click to expand...

5 to 7 ppm phosphate is a little high but nothing to lose sleep over. I started dosing 6 ppm because of Green Spot Algae is starting to form on the glass. Don't trust the test kit unless you calibrate it first.
 
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