Are you far enough south in Texas that your tilapia are surviving through the winter?

If so, your 30 pounds of tilapia should expand greatly this summer with at least several hundred pounds of spawned tilapia that will be eating algae this year.

OTH, if your tilapia are dying off during the winter, you may need to scoop the floaters and discard them. Each fish contains a lot of nutrients.

Also, when you groom the shallows with a sand rake, do you throw the algal mats out of the watershed of the pond? If not, then all of those nutrients are going back into your pond as the algal mats decay on the bank.

(Most of the people on the forum that rake, say there is a sweet spot in the timing to remove the mats. Let them dry a little so they get lighter to move, but not so dry that the mats break apart when you attempt to pick them up.)