I have several questions

First off I have this system as my RODI Residential RO - Under The Counter Reverse Osmosis Systems , I was wondering if this is a good system to use for water, 2nd I have a sandsifting starfish that hardly moves and when I say hardly moves, I mean it, I almost have to get a microscope to see him do anything, Is he suppsed to be that slow? and 3rd, I have 2 Koralia #3's in my 125gal, do you think that is enough flow for soft corals?

 

you will need a dionizer to help lower other unwated dissolved solids.

my starfish sometimes sits there for 3 days in one spot.

 

i have some sps in my 72 gallon and i have 2#3s and 2#1s but for softies only it might do for now, you can always add more if you find lots of dead spots in your tank.

 

How will I know if theres dead spots?

 

is it possible to add a dionizer to it?

 

Flip the sandshifting star and see if he can flip himself back. It's cool to watch.

 

Your RO system can be modified with a few minutes and a few $$. First you do not want your aquarium water to pass through the final GAC taste and odor filter or the pressure tank as both contribute to higher TDS. You should also add a DI filter to lower the treated TDS to 0.
This is easily accomplished by installing a small 1/4" tee, ball valve and check valve between the RO membrane and the final taste and odor carbon filter and installing the DI filter and ball valve off the other leg of the tee.
This still gives you pressurized RO only water for drinking but also gives you the option to fill containers like buckets or jugs with RO/DI for aquarium use.

Here is a simple diagram showing what I mean. Notice the tee after the autoshutoff valve which then leads to either the storage tank fro drinking water or the DI for reef water.
http://www.spectrapure.com/huds/DWK-DI-AX.pdf

Here is another one with a little more detail, the only thing I don't see is a ball valve on the DI out line so you can shut DI flow off.
http://www.spectrapure.com/huds/4-STAGE-DWK-RODI-NAG.pdf

 

Detritus build up and algae growth.