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Need Help!! Phosphate off the Scale!!

1989 Views 5 Replies 3 Participants Last post by  ShaneSmith
I just picked up a new Hagen Nitrate and Phosphate test kit for my
29gal. I just re-started my tank with fresh gravel and new plants and
lights. I have 95watts, and DIY C02. I also completed a 50% water
change yesterday, and another 25% waterchange today, because of a
small thread/ hair algae outbreak. So I wanted to make sure my water
was clean before testing. The tank has been running for 6 weeks,
cycled and has a good bacteria load going for sure. Maintenance is
kept up religiously. Plants were growing for a couple of weeks, but
are showing signs of slowing down, and yellowing.

Readings are as follows: (after water change)
Ammonia: 0ppm
Nitrate: 0-5ppm
Phosphate: 5ppm+
Nitrite: 0ppm
PH: 7.0
GH: 8deg
Kh: 9deg
c02: ~20ppm
Fish load minimal: (4 Cardinals, Pleco, and a Cory)

Problem here is obviously the Phosphate!! I tested my tap water and it
came back zero. Then I did a test in the tank (after the water
change), and it was off the scale?!! I dont get it! Something is
really leaking Phosphate into my tank...and I dont know what? I have
fertilizer spikes under the plants which have Phosphate in them, but
they are way under the gravel and are never disturbed.

Someone told me that Activated Carbon in your filter releases
Phosphate, but I found that hard to believe as Activated Carbon is
supposed to suck up nutrients rather than release them right???

I'm really stuck on this one! Can anyone give a list of possible
sources of Phosphate, that I might not be considering. At present, I
am not dosing any ferts, and havent since start up. The phosphate just
magically appears for no reason!

Thx in advance,
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1 - 6 of 6 Posts
What is the fish load? How often and how much do you feed? Describe the plant mass / density. How are the plants doing? How much light? High pressure or DIY C02? How old is the charcoal?

If you are not dosing any ferts and one or more are at 0 then your plants may not be able to consume the P fast enough? It may simply be a case of having a shortge of some other nutrient.

Jay Reeves
Plants are Osirus, Vals, Tiger Lotus, Sprite, and Java Fern. Feeding is very minimal b/c of only 7 fish. Feeding 2-3x a week, and a very small pinch at that! Other specs can be found above...

When I started this tank, everyone said to be sure to add root tabs, and when I did everything went haywire. Why would the plants use all the Nitrates in the tabs, but none of the Phosphate?

At this point my Nitrates are at 5ppm and Phosphate at 5ppm. So should I increase my Nitrates to 50ppm to reach that 10:1 ratio??

I'm severely mixed up!
Sorry, I missed that you had some of the stats in your first post. I wouldn't add any N. Don't worry about ratios right now. You could vacuum the top 1" or so of gravel in case any of the fert tabs are causing increased P. I used the Jobes spikes once and had some problems, but know that some folks really swear by them.

C02 is OK if your test kits are reasonable. With 3.28 watts per gallon you probably need to be adding some water column ferts. You may need potassium and traces.

Ask your water utility to fax or email you a list of the contents of your water. My water has less than 1 ppm P, but some communities may add more. The lost of what is in your water is handy to have in any case.

If I remember correctly Tom B. has driven P levels to 5 or higher without problems as long as other nutrients were available and as he would say - check your C02. Make sure your test results are reliable.

Jay Reeves
So last night, I did a another 50% water change. Filled the tank again, and did another 50% to dilute the phosphate again. It kinda half worked. The readings came down to around 2.5ppm from over 5ppm. I also took all the carbon out of my Penguin filter insert, and took all those damn Nutrafin spikes out. I looked at the box again and the reading were 16-9-12 (NPK). That doesnt seem like a 10:1 ratio to me! And on the back there was two different sources of phosphate.

I also cut the lights back by 60% (turned off the power compact), until I can get my ratios right. I hope that doesnt kill my plants. I added some N as the readings were zero after those huge water changes. Readings were at 5ppm this morning, added a bit more before leaving for work. When I can get them up to 10 or more I'll turn the light back on.

I think I need more fish too. My plants are eating my Nitrates faster than my fish can produce them. With 95watts over 29gallons, I will need some heavy fert dosing. I rather just have more fish to help out with!

Keep you posted on the progress
Nick D
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Don't add more fish unless you want more fish. You need to get a half pound or more of KNO3 and you need to get a lot of flourish and flourish Iron or something else of the sort. I would also get some fleet enema. Dose your tank according to the estimative index and things should work themselves out. Keep doing waterchanged in the meanwhile to get things in a good ratio. the plant spikes would have eventually run out of nutrients so i think it was a little rash to take them all out.
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