With that being said, I've had algae and had 0 phosphates and 0 nitrates long ago but I did a few things and it went away. First I changed my food. If you use frozen brine etc., I let mine dissolve in a small cup of RO
water and then only fed the actual chunks of food. I also changed 20% of my water weekly. I cut back 2-3 hours of lighting ( changed bulbs so that may of helped), added an extra powerhead, because red algae doesn't do well with high water flow. If its truly red, then it's probably cyano
. It takes a little while to get rid of.