Join Date: Jul 2016
Location: Copenhagen, Denmark
Who's eating my PO4?!
I'm having some odd issues with PO4 in my tank.
A little info, and background story:
I'm runing a high light, high CO2 tank with a lot of plants. I'm dosing daily with Tropica fertilizer(with NPK), and adding another brand for micro, as it seems too little micro is present in the Tropica.
Some time ago, I started getting some GSA, so I tested the water. Nitrates where fine, around 30~40 ppm right before waterchange, but PO4 was way low around 0,5 at most.
I hooked up some PO4 fertilizer to compensate.
It's been running for a week now, and it seems the GSA isn't going anywhere, seems to even spread faster on the not too old leaves. I did a new test and PO4 is still low.
What puzzles me is the amount of PO4 I'm dosing, just doesn't make sense compared to my tests of the tank water.
I'm dosing the easylife fosfo wich states 10mL per 500L tank is 0,1 ppm.
My tank i roughly 350L, so if I shoot for 2,0ppm PO4 the math should be like this:
10mL per 500L = 0,1 ppm.
10mL per 50L tank = 1,0 ppm.
70mL per 350L tank = 1,0 ppm
140mL per 350L tank= 2,0 ppm
The above example is my 350 L tank.
Now I'm currently dosing 50mL A DAY of the PO4 alone, on top of that I run the Tropica NPK ferts, and I often feed the inhabitants frozen foods which also has quite high traces of PO4.
I should have readings of around 5,0 ppm PO4 at the end of the week minus what the plants are using.
However I'm still getting readings around 0.5 ppm.
I've tested with to versions of testkits and an electronic tester with a +/- 0.1 ppm margin.
I'm really shocked seeing the PO4 getting used up like that, is this normal plant consuming this much PO4? Are my calculations way off?
What steps do I take now?
Add more PO4?
Empty the tank and look for a phosphate-eating creature in the gravel?