2 questions

first, after my water has run through my RoDI filter I am getting a reading of .07, does this mean it is time to change something? For about the last month I have been getting increasing amounts of hair algae and I can't seem to determine the culprit. I know that if your RoDI water is not great this can be a cause so is .07 too high?

Second how do you add your chemicals. For the last month or so, I have been turning off my main pump so that when I add it, it gets to spread around in the tank itself and nothing gets lost to any filtration. But when I do this my corals never look very happy afterwards.

Thanks for your assistance.

 

What chemicals are you adding and what quantities?

 

See above comments in red.

 

First there are no decimals so it is 7 TDS, what appears to be a decimal point is actually a power ON indicator light.
Yes, you need new DI at a minimum but before doing that we need more information to help you make the right decisions.

How old is the system and when were the sediment andcarbon filters last changed and the system disinfected?
What is your tap water TDS, RO only TDS before the DI and final RO/DI TDS? Make sure to rinse the TDS meter in distilled or RO/DI between each test so you have a clean probe and accurate readings.
Sediment andcarbon filters really have nothing to do with TDS, they protect the RO membrane from sediment, particulates, colloidal materials and chlorine but they need to be changed every 6 months or so or the membrane which does 90-98% of the treatment will fail.
What is your water temperature and your water pressure? What is your exact measured waste ratio using a measuring cup and clock or watch for exactly one minute from the waste and the treated lines?