P and N high

hyla84 · May 1, 2019

Hello everybody,
I have a 400 lt tank, doesn't matter how much water do i change, P and N doesn't drop.
Any idea what to do?
Thanks in advance

Reefpuck · May 1, 2019

Need more details such as your setup, live stock, running any media, etc. Also how high are your P & N?

beaslbob · May 1, 2019

hyla84 said:
Hello everybody,
I have a 400 lt tank, doesn't matter how much water do i change, P and N doesn't drop.
Any idea what to do?
Thanks in advance

water changes will never keep p, nor n, nor anything things else building up or being consumed at 0. The tank will simply reach a point where the amount of 'stuff' removed is equal to the change between water changes. For example, if nitrates are increasing at 5ppm between 10% water changes with 0 nitrate water, the tank winds up at 50ppm nitrates before the next water change. Down to 45ppm them back up to 50ppm before the next water change.

In order to maintain things that change, the change between water changes must be 0. In the case of nitrates and phosphates, various algaes like macros do a nice job. In the case of calcium, alk, and magnesium, various dosing methods (to replace them as they are being used up) work nicely.

my .02

hyla84 · May 1, 2019

So if I change 200 liters of 400 the values should be half. But it doesn't happen

beaslbob · May 1, 2019

hyla84 said:
So if I change 200 liters of 400 the values should be half. But it doesn't happen

most test kits can't measure small changes.

Plus there may be nitrates/phosphates in the replacement water.

hyla84 · May 1, 2019

Tested the water with Hanna hi736 phosphorus and no3 with elos both tank and ro water. An ats can be useful? Why do they are so high? I'm talking of po4 2.0 and no3 over 25