Yes clearly DI water is much much better than tap. It is the closest you will get to pure water.
BTW while it is still up for debate I wouldnt suggest drinking DI water. Several theories think thats its not good for the body.
Originally posted by Hiddenicon
Tizzo, i wanted to know if RO was better than tap at keeping algea down
Without a doubt... This pic is taken of my bro's tank. All of his "testable" water params were fine (except DKH, but that's cause he adds a ton of buffer). He does water changes way more than me, yet this stuff just keeps comin'. Oh, and BTW, that rock was a coral skeleton. Bleached. Should be bright white...