I've had my 75gpd RODI setup for about 6 months and i just noticed there's a very significant drop in performance and I'm wondering if anybody knows of some tests that can be done to figure out what's wrong?
5 stage RODI - 75GPD - currently producing 0TDS with 1-2TDS after the RO. I've flushed the membrane routinely and pressure has dropped about 5psi and sits around 40psi.
It's still producing a steady drop..... drop..... drop but it used to be much faster. I'm hoping it's just new pre-filters that I need but i've heard funny things regarding broken Auto Shut Off's and such.
thanks.
now I know nothing about these, but shouldn't it read 0tds after the di (I assume that's what you meant because I assume the di is the last stage )? I though the ro removed anything left
To figure out where the problem lies you need to check the pressure throughout the unit. Detach the tubing after the pre-filters and check the pressure. Next check the pressure right before the membrane and then after the membrane and so on. This way you can find if there is a blockage somewhere along the line. Turn the feed water off before detaching anything or you will soak yourself as I'm sure you've already discovered ;)
Performance can drop with the temperature of the water. If your feed water is very cold you can buy a 25 foot roll of tubing from Home Depot ($4.99) and run it between your water line and the RODI unit. Submerge the tubing (coiled) in a bucket with warm water and see if that improves the rate of production. I put the tubing in my salt water mixing bucket next to the unit with a small tank heater in it. Don't run hot water through the unit, you can ruin the membrane.
Alternatively, it may be the membrane itself. I have that problem as well, it takes me 36 hours to produce a 9 gallon bucket of water. The tds is 0 after DI so I don't want to buy a new membrane but it is a nuisance.
My 75gpd produces a steady flow of "good" water at 35-55psig. My pressure range is due to my well pressure system. For more water I line up a second 75gpd and a booster pump to get 75-80psig.
Now as for why your system is slow, you will have to systematically go through it one piece at a time until you find the problem.
I've taken a closer look at my RODI and i believe my DI is done and the filters probably need changing. I recently tested my water and it was reading around 1-5ppm on the old TDS'o'meter.... however.... after cleaning out the whole reservoir and forcing it to fill it up from scratch i noticed that I was actually receiving 30-50ppm when the system first kicked off, which means my DI resin is totally shot.
After the RO pressure built up the TDS went down to 1-2 and that's what's coming out now but i'm sure i was putting essentially small amounts of unfiltered water into the tank via Top Off and W/C's. This may also be a potential cause for my SPS issues recently too. we'll see.
Question: Does anyone know what 'disolved solids' would get through? or is it a total mix bag? I mean is it possible that copper or Chlorine got through or is it likely just phosphate or other minerals?
I'm currently ordering a new set of filters and DI but it will take a week before i can install it, hopefully things dont get worse.