How to drastically lower phosphate?

[Guiids]

Hello everyone!

I hadn't checked my phosphate in a while and started growing large amounts of (hair?) algae, see video. I checked and it's sky high!

A few qs:
Where do we think this is coming from? I make my own RO water, could the filters be spent? I'm replacing today.

How can I massively lower this? I assume a huge water change like 80% after I replace filters?

What's the recent opinion on adding solutions to lower phosphate, should I also do that?

Is 1 full fish cube per day too much and causing this creep? See fish and tank size below.

Video of algae/tank:


Tank size: 65 gallon, did 40% water change 2-3 weeks ago, prior to that the tank had not had one 3-4 weeks.

Fish: 2" fox face rabbit fish, inch long box fish, 2 half dollar size damsels, watchman goby/pistol shrimp, cleaner shrimp, 6" engineer goby, 2 urchins (purple spike and long black spike)

Parameters:
Temp 78F
S G 1.027 (adding RO to 1.026)
pH 8.1-8.3
NO3: 75 ppm!!
PO4: 1.03 PPM!!!
Alk: 200 dKH? Using strip
Carbonate: 80 KH ? Using strip
Hardness: 150GH? Using strip

Thank you in advance!
Joe

 

[Lavey29]

Water changes do virtually nothing to lower phosphates because they bind in the rocks. Do you feed coral supplements like reef roids? What is your export process? Phosphate RX works well for me.

Strips are useless for testing

 

[Randy Holmes-Farley]

I'm going to close this thread,. Please do not start multiple threads on the same topic in the same forum.