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17 Posts
Discussion Starter · #1 ·
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,

17 Posts
Discussion Starter · #3 ·
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!

17 Posts
Discussion Starter · #5 ·
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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