Seachem Matrix Biomedia affecting nitrates and phosphates

[DEL 707]

I'm sorry, I didn't know whether to post here, or in the filtration sub forum.

I have a 3 month old, 56l reef tank.
I having a heck of a time with cyanobacteria and dinos. Nitrates and phosphates hit 0.
I've been slowly dosing Reef Zelements Nitro+ and Phos+ for just over 2 weeks. Dosing daily, I've managed to get my nitrates up to 5-10ppm, but my phosphate levels have not budged. I've been upping the dosage slowly, but right now I'm at 14ml a day with no improvement.
I've been using 2 different phosphate test kits, Redsea and NT Labs.

Filtration wise, I have 8kg of dry rock and 2 weeks ago I added 500g of live rock rubble.
I have a canister filter, a fluval 107. I removed all the finer sponges, but kept the coarser stuff. I also added Seachem Matrix Biomedia and Matrix Carbon.

Someone said to me that the matrix biomedia was acting against me, removing my nitrates and could also be affecting my phosphates.

Should I remove the biomedia?

 

[Randy Holmes-Farley]

There’s no normal biomedia that will do much for phosphate. I’d just dose more.

But if you are dosing ammonia or nitrate, the media is not likely beneficial in any way.

 

[VintageReefer]

Your 3 month old dry rock could be binding phosphates. This can take several months before it stops

How is flow in your tank? Cyano often develops when there isn’t enough water flow