Do I need a DI addon for my RO unit?

[serbusfish]

Today I purchased an RO unit from my LFS (this one http://www.theaquariumsolution.com/50-gallon-ro-unit-ro-50)

I asked about de-ionization and the chap told me he uses this model RO unit and that the de-ionization add-on shouldn't be needed for water in our area. I looked on the website of my water company to find out what was in my water and it doesn't same if they use chloramines, which worries me.

This is the data they provide:

http://www.stwater.co.uk/my-supplies/my-water-supply/water-quality-in-your-area/?postcode=DE5+3DJ

In your opinion should I opt for the DI add-on? Or should the unit be fine on its own?

[ca1ore]

I would always use a DI final stage. Unlikely that your post RO water is at 0 TDS, so there will be something for the DI to remove. If your water is good, your resin will last a good long time.

[serbusfish]

I would always use a DI final stage. Unlikely that your post RO water is at 0 TDS, so there will be something for the DI to remove. If your water is good, your resin will last a good long time.

Right ok thanks I might have to pop back and get the add on then.

Btw, I am new to keeping marines so this is probably a dumb question, but is it ok to use cold water with the RO unit? I only ask because in the instructions it says:

'the membranes are rated for flow at 25C. At lower temperatures all RO units used will produce a decreased flow rate by approximately 30% at 15 centigrade and by 50% at 9 centigrade.'

Its seems like a no brainer as they tell you to connect the unit to the cold tap, but then this information about temperature confuses me?

[julie180]

DI is a good choice. Yes, you want to use cold water. During the winter, water production can go down due to colder water entering the house. Its not a problem, just an inconvenience.

[ca1ore]

Right ok thanks I might have to pop back and get the add on then.

Btw, I am new to keeping marines so this is probably a dumb question, but is it ok to use cold water with the RO unit? I only ask because in the instructions it says:

'the membranes are rated for flow at 25C. At lower temperatures all RO units used will produce a decreased flow rate by approximately 30% at 15 centigrade and by 50% at 9 centigrade.'

Its seems like a no brainer as they tell you to connect the unit to the cold tap, but then this information about temperature confuses me?

Definitely connect your RO to the cold side. I'm not an expert on the intricacies of these things, but since my water is well-sourced, and averages about 55 degrees (pretty much year round), I do see slightly reduced output from my unit, but its not a biggie. Low water pressure will also rob you of capacity.

[serbusfish]

Definitely connect your RO to the cold side. I'm not an expert on the intricacies of these things, but since my water is well-sourced, and averages about 55 degrees (pretty much year round), I do see slightly reduced output from my unit, but its not a biggie. Low water pressure will also rob you of capacity.

Ok thanks, I have purchased an adapter which will let me use the RO unit on the kitchen tap rather than have to use it outside.

Now what I am wondering is if I tested the RO unit now would I need to keep flushing it every few weeks until I set my tank up? Or can I leave it filled with water and just flush it when im ready to use it again?