So I just figured out why I have cyano and other unsightly algae in both tanks at school and why my DI resin was going bad so quickly. I can't recall when I replaced the RO membranes on the RODI, but when I did I somehow mixed up the clean water output and the waste output on one of the RO membrane housings. I couldn't figure out why the TDS was reading 200-300 on the DI input. How I mixed these up and missed it for so long is beyond me, but lesson learned and I can't wait to have a clean tank again!