I just can't figure out what is going on...
I've been working on getting a good dosing regimen going and been dosing (and testing) regularly with Plantex, KH2PO4, K2SO4, KNO3.
On Thursday, 21/10, I had a PO4 reading of around 0.6 to 0.7. Did not dose PO4 (only dosed 5mg/l NO3).
Yesterday, I bought and installed a new Eheim 2026
because I had been feeling for a while that my "built-in" filter on the 200l tank was just not circulating enough water and not doing such a great job at mechanical filtration.
This morning I tested PO4 and came up with 3.5-4 mg/l!!
. I retested and even created a control solution and tested against that: PO4 test is ok.
So what in the world has suddenly raised my PO4 level like that??
In the 2026 I put (in order of filtration) Eheim's "noodles", coarse sponge (that came with the filter), JBL MicroMec sintered glass balls (a product that I've been using for over a year), then JBL filter floss and finally the white pad that came with the filter.
Could it be that previously the circulation was so bad that "pockets" of PO4 were in the aquarium and not being measured and that with the improved circulation the test kit is now picking this up? Or can a filter material carry phosphates?
Seems far-fetched but I can't think of anything else? Anyone else?