RO Membrane

[zebrafish]

I was wondering if anyone knows about how to tell when it is time to change the Membrane on a RO unit. The instructions say to change it every 1.5 to 2 years or when the TDS reading is above 30-40. What is TDS and how do you check for it?

I am starting to get red slime algae in the tank and can only think of the RO units causing the algae. I have kept the same schedule for everything with the tank. Parameters are fine, do 10% water change every 2 weeks.

 

[crpeck]

The only way to test TDS is with a TDS meter. They're not expensive and anyone trying to make their own RODI ought to have one.

Our water is good in Memphis so you really shouldn't ever have to change the RO membrane on the early side. That warning is for people on wells and such.

The RO filters should be changed every 6 - 12 months depending on how much you're running through them.

 

[swalker]

Cathy is exactly right! Here is a link to one place to get a TDS meter.
http://www.marinedepot.com/md_viewItem.asp?idproduct=RO1351

If you use Ebay you can get one even cheaper or one that installs directly on your RO unit.