RO/DI--people who have it can you help me?

[sharuq1]

Ok so I have my new aquasafe unit setup and it has been up for about a month or so. At first my readings for TDS were 0, but lately they have been slowly climbing. My last reading was at 006ppm. Is this normal? I mean it hasn't been long, I expected the unit to perform optimally for longer than one single month. I have been using about 5-10g per week. Is there something I don't know, or do filters or DI really need to be changed every month??

[littlesilvermax]

Is the 6 ppm before or after DI?

[Delphinus]

Are you backflushing the membrane periodically?

It depends on your source water how long your prefilters will last. I find I get a few months out of mine, my source water TDS is around 180-200 I think. 6 is not an uncommon reading for the RO output, but I find in my case usually what happens is it's more of an initial surge right after turning it on, it settles down to zero after 30-60 seconds.

DI output is always zero though unless it's spent. Ie., if you're getting 6 after your DI then it's time to change the DI. You should be getting way more than a month out of your DI. I don't have an Aquasafe unit but I get at least 6 months out of my DI cartridges (to give you an idea of what is reasonable to expect).

One note, is your unit directly plumbed to a float valve on your sump? Because if it is, this is very hard on a RO membrane. The constant on/off cycles is very hard on the membrane. I found this out when I had to replace mine 3 times in a year. It's better to have a reservoir that feeds the float valve on-demand as per evaporation, and fill the reservoir in a single go when it gets empty.

[Myka]

What is the TDS of your tap water? What psi is the unit running at?

[digital-audiophile]

I've found similar on my unit that I just set up a couple weeks back. I am getting TDS of 2-4 with brand new media.

[Delphinus]

Between the RO and DI or after the DI?

[sharuq1]

The tap TDS is about 225 or so I think. The 6ppm is what is coming out of the unit, after the DI and polishing filter thing. Should I take the "polishing filter" off the unit? It is on after the DI, then the DI goes to the storage container dealie. (not sump, this is the container aquasafe sends with their maximus unit for home use).

I haven't checked psi (I don't know how, especially without spraying the house down with water i see no where I can put a psi measurer thingie) , but I really don't think the psi is the problem as I was getting 0 reading before and I am in the city not the country.

I don't know how to backflush the membrane.... If backflushing means turning the wastewater as high as it can go for a few mins then yes I have done that, but it didn't help.

The unit is plumbed into a tap and is turned on or off using the valve that is on the input line. It is not hooked up to a sump or anything like that. The DI does look like it is almost exhausted, but I just don't know why. Should I be turning the wastewater so high that it is a flow and the RO coming out is a mere occasional drip??

It looks just like this unit:
http://www.aquasafecanada.com/MAXIMUS%20II.jpg
http://www.aquasafecanada.com/MAXIMU...TOP%20VIEW.JPG

[Myka]

Check the tds of the the water that comes out of the RO, but BEFORE the DI. You'll have to take it apart to do that. Just disconnect the line between the RO and the DI, and collect that water to test it. How many gpd is your RO?

[sharuq1]

TDS there is 18. The unit is supposed to be 100gpd. Also TDS before "polishing" filter (after DI) is same as what is coming out when polishing filter is hooked up, so guess it isn't that.

[littlesilvermax]

Originally Posted by sharuq1

TDS there is 18. The unit is supposed to be 100gpd. Also TDS before "polishing" filter (after DI) is same as what is coming out when polishing filter is hooked up, so guess it isn't that.

If your post RO tds is 18 ppm, then you have one of three things:

1) very high tds water (like 600 or so) and it exhausts your DI quickly
2) a bad membrane (FWIW the 75 gpd, I like the Filmtec, seem to consistently outperform the 100 gpd ones)
3) very low pressure to the unit

How to solve the problems:

1) just have to live with it (BTW someone around here has awesome deals on DI resin)
2) get a new mambrane, and by the sounds of how much you are using stick with the 75 gpd ones
3) get a booster pump

FWIW even if your pressure is good, a booster pump wil up efficiency, that is why I bought one.