Now I wonder if the raised aluminum is from the bio blocks lol dammit! I still have 3 bio blocks in my tank under my live rock, do you think removing one a week would be too fast?If i was you, i will try to control Nitrate first, my magic # is less then 4 ppm , but NOT less then 2.5 ppm, then you deal with PO4 , after you got some Nitrate , they gone balance , Chaetto will be a way to aggressive , will take everything , NO3 and PO4 and the MOST what corals need, you will lose color for sure, i use to grow Chatoo , one or two 5 Gal. bucket in 90 gal. refuge.
Very, very gentle dose ( add. Potassium Nitrate, pharmaceutics stuff , i got in e-bay).
Those blocks u mention, lots of ppl. complain , release Aluminum , NOT to mention got full of DETRITUS.
4 x PO4 remover, is a great product, wont release iron , like 99% of GFO, ROWA is good also , but aggressive.
First and first, make sure your NO3 test , is just fine, i use list 2-3 dif. tests. compare.
Every tank is dif.
Try to read the health of corals by eye, i know is NOT easy.