High phosphate?

I switched out tanks about 3 weeks ago, never had problems with phosphate in the past. Changed 2 things when I went to the biocube. Now using ro water and a sandbed. So Im thinking the sand is leaching out phosphate. How do I get it back down. Water changes dont seem to be doing the job. I put phosban in and doesnt seem to work that good. thanks

 

just a media bag. Food is only about a month old, I use rods. My 120 is still set up use the same food on that and phosphate is at 0 I really think its the sand. I used 20lbs of the black sand you get from petsmart along with a 1lbs bag of white sand cant remember what kind it was. the bag looked old though.

 

found the source. My water ph is high so before I put it in the tank, I was adding a half tablet of tank buddies 7.0 that brought the ph down to 8.2-8.4 tested the water after adding one and raised the phosphate to 10 from 0 in a five gallon bucket. What can I add to bring ph down without spiking phosphate. thanks

 

Thanks that works great, and didnt even have to spend money. Also had big phosphate drop with a 5g water change, and I think the phosban worked to because it was also down a little from 2 days ago when I checked.