J
You have the CO2 down, you have the lighting down.
You have the traces down.
All that's left are the macro nutrients.
The CO2/light/traces don't work without the NPK being in a good range also.
Algae are good at living at high levels of these and also very low levels.
K2SO4-you can get it from turf supply companies for about 20-30 for 50 of fine power which quickly dissolves.
50lbs will last you, your kids and maybe your grandkid's tanks provided you are still quite young.
You can also get it and the others on line at
www.litemanu.com.
Potash of sulfur is the common name.
Garden centers carry this under the "Green All" brand, about 5$ for 10lbs.
KH2PO4, can be bought from litmanu.com.
You can also use Fleet enema from a drug store for sodium phosphate which will work well.
KNO3, stump remover, available at Homer Depot, garden centers etc. I like the Grant's or Cooke's brands.
All three of these are available from turf supply stores for 15-25$ a 50 lb sack.
Many lifetime's supply.
These allow you to what ever amount of NO, K, or PO4 you want.
I add these dry, like adding a 1/4 teaspoon of baking soda to home made cookies.
It really will help your plants grow much better and look better also. You'll get higher O2 levels in your tank/less algae also.
Regards.
Tom Barr