I purchased a ro/di 6 stage system for my reef tank and before filling it I let it waste about 5 gallons tested it and got no ammonia or phosphate readings so I started filling up my 150g tank and 55g sump with water. I was surprised after only a few days I had a testing of ammonia so i figured wow i started cycling already (never thought too much because i had lr & ls so i figured thats what kicked of the cycle) well anyhow i kept testing for the next several weeks and saw the ammonia spike very high then the nitrite and then the nitrate, however i still had a reading of ammonia and trite when the trate spiked (very minimal reading) but i just figured the test kit i was using was wrong since i've read multiple postings saying these test can be off (meanwhile i was topping off daily with fresh ro/di water). Anyhow, after my trate spiked real high i figured time to do a water change (even though my amm & trite had low readings that werent going down) so i got it all set up in my brute can added the heater, 2 power heads and IO salt and let it go for 24 hours, next day i take my readings and sure enough i have an ammonia reading!! So I went and purchased new di refill figuring it must be time to change it. I received it and changed it out and used it for a 30 gallon water change on the tank last week and it read no ammonia (coming straight out of the unit and then after i mixed it up with the salt) so i thought woohoo i was right and the di needed changed but then yesterday i filled up and mixed another 30 gallons for a change i was going to do tomorrow and it read that it had ammonia again so I tested the water again from the unit and sure enough i got another ammonia reading...what would cause this after only using 30 gallons with the new di resin and how can i fix it? Im concerned because I do daily top offs with this water and have another 30 gallons sitting for a water change to do tomorrow. Also recently Ive had an outbreak of the red slime, is this what is causing it and how do i get rid of it before it takes over my tank? Any help would be greatly appreciated since im stumped...thanks in advance!! 
Heres a pic of my baby
Heres a pic of my baby
