I've battled cyanobacteria (blue-green algae) the whole time I was in Charlotte... the tap water was ripe for it...
On the 300 gal stock tank I used a BioForce 2000 Pressurized Pond Filter with a Mag 18 pump pushing water through it. It was basically a FX5 on steriods...
I used anywhere between 1~3 250~300W heaters depending on where/how I had the system set up. A couple of times I had it in a fish room where the ait temp was maintained around 80*F and then it needed little to no heat... other ties, such as in that pic, it was placed openly in my home and then I used the max heat mentioned...
The plasic walls held heat a bit better than a glass aquarium but the uncovered massive rippled surface area allowed a ton of heat loss.