When to change RO/DI membranes

My TDS is starting to rise the more water I make. It is now at 10 up from 1 or 3 before. I have noticed some more algae growth. At what level should I get new membranes? Also I just put a new batch of phosphate remover into my phosban reactor could this slow the algae growth?

 

You probably don't need to change your membrane....probably just your DI resins. Do you have the ability to test your water after RO but before DI?

 

No I don't I think I might also need to change my prefilter it is pretty nasty. Also I check on Dr.F and S and they do not sell Di resins.

 

You change the RO membrane when it can no longer produce water that is approx 94 to 96% rejection in most cases. This is the point where the cost of replacement DI resins start exceeding the cost of a new RO membrane if you make much water. Another sign is reduced production or GPD due to a fouled or plugged membrane. If your pressure and temperature are still the same but production is dropping off even with replacement filters its a sign its time.

To know your rejection rate and membrane condition you need to know what RO membrane brand and model you have, your tap water TDS, water temperature and water pressure. You also need to know your waste ratio as often its too high thus reducing system pressure and GPD since its going down the drain and not through the membrane.

If you can supply the above I can help you determine your membranes condition.

For replacements, both filters and DI resins check here:
http://www.spectrapure.com/email/customer-appreciation.html#1

They don't come any better or at better prices and they are a 3Reef sponsor too!

 

I have a coralife pureflo 2 will the spectra pure di resins work with my unit?

 

According to my manual from airwaterice. ... they suggest changing filters when TDS is about 10 % of the tap TDS.

 

Yes. Spectrapure DI resins will improve any unit.

Prefilters and carbons have very little to absolutely nothing to do with final TDS, thats the job of the RO membrane and the DI resins.
You cannot go by TDS for changing the prefilter and carbon.
For membranes 10% of tap water TDS would be way too high in most cases. Think about this, the average TDS across the country is about 250. If you wait until 10% thats a TDS of 25 either going into your tank or hitting your DI resin. not good either way. In may case my tap TDS is over 800 so 10% would be over 80, no way in heck am I putting that in my tank or DI filters.

Change the RO membrane at about 5 or no more than 6% of tap TDS in most cases if not sooner. My Spectrapure membrane is averaging 99.35% rejection or removal efficiency with RO only. I will change it at no worse than 97% if not sooner as it will be costing me a fortune in replacement DI resins at that point.