tds

I was talking ro the guy who works on the ro unit at my work and he sad that the tds is 3 is this good to use in my tank without getting the brown stuff. I know 0 is what I want but is the highs level I can use

 

Here's a good read on TDS:

What is TDS? by Randy Holmes-Farley - Reefkeeping.com

 

Since TDS is not a measure of anything specific its hard to say if its good or not. You must also remember RO membranes are not particularly effective at certain things like silicates, phosphates and nitrates so they can be getting through and may not show up on a TDS meter since they are weakly ionized, they don't have a strong electical charge.
It really takes the combination of carbon, reverse osmosis and deionization to get everything and its inexpensive to add DI to a RO system.

If you are using a pressure tank, as in a drinking water system, that is also not a good idea for reef water since pressure tanks lead to TDS creep and higher than normal TDS over time due to frequent cycling on and off to fill the pressure tank. It may start out at 3 TDS but it climbs from there and concentrates in the pressure tank.

 

does buffed water make the tds go up

 

Yes, anything you add to the water that dissolves adds TDS.

 

ok thanks