New RO/DI system and Clueless Operator

[Dr. D]

I bought a 100 GPD - 4 Stage "Professional" RODI system from SaltwaterAquarium.com. It has an inline TDS meter, auto-membrane flushing, and a booster pump. I spent the money for this one because I wanted a turnkey approach that I couldn't screw up. But I'm a professional-level screwer-upper, and somehow things aren't going well.

I understand the direction of flow, using cold water, and the basics of TDS. I initially drew water from an indoor faucet, and things went great initially. I got the folling readings from the unit's TDS meter:

I didn't understand only the second reading was higher than the first (it was always a few points higher, though both numbers fluctuated slightly), but was happy with the zero TDS output, which I proudly displayed on my build thread. All was fine for about 40 gallons into the 100g tank, then I started to notice much higher TDS output , along the lines of 40-70 TDS. That's when I realized the purpose of the pressure gauge... and I had horrible pressure, around 20-30 psi. I fiddled with the silver knob at the top-- if the unit came with instructions I don't see them-- and figured out which direction increased flow. Still, I couldn't get above 40 psi. This is the unit, off at the time of the photos:

I wondered if my indoor 1/2" faucet pressure was the problem, so I connected the system to an outdoor spigot with great water pressure. No improvement in output TDS.

What am I doing wrong? This is a brand new unit used for only a few hours. I'm guessing the problem is me.

Help!

 

[dedragon]

did you flush the ro membrane for a while before turning the unit on? Looks like you maybe forgot and depleted the di resin (which changed color)

 

[Shirak]

Will have a look at the connections but from the color of your DI canister the 0 reading was because it was removing the stuff from 90TDS water. Which as you found out lasted about 40 gallons. So there is something with the connections that is sending tap water or waste water to the DI canister.

 

[Dr. D]

did you flush the ro membrane for a while before turning the unit on? Looks like you maybe forgot and depleted the di resin (which changed color)

No... I don't know how to do that. I also took (false) comfort that it said it auto-flushes. How do I do that?

 

[Shirak]

Can you get some pictures of the other side of the canisters and the pump and RODI housing connections? Where is the TDS meter number 2 installed? I see one goes into the sediment filter?

Connections should be.. line water to booster pump in.. pump out to sediment filter.. sediment to carbon block filter... carbon block to RO housing in. RO water out to DI cartridge and Waste water out to flush valve/drain. On the RO housing on the output side there are two connections. There is one in the center and one on the outer edge. The center is RO water and the outside edge one is waste water.

 

[Dr. D]

Will have a look at the connections but from the color of your DI canister the 0 reading was because it was removing the stuff from 90TDS water. Which as you found out lasted about 40 gallons. So there is something with the connections that is sending tap water or waste water to the DI canister.

A DI canister lasts longer than 40 gallons of filtered water, right? I did nothing to the fittings except plug in the (blue) source water line to the "Step 1" canister connection and the (clear) output line to the Step 4 connection. The black waste line was already hooked up, and I did nothing to that.

 

[Shirak]

I think what Dedragon is getting at is something called TDS creep.

When the system is off the TDS inside the RO housing balances out. The first gallon of RO water out will have a high TDS before it drops to normal TDS range which should be around 4ppm. Many users put a bypass line in before the RO goes to the DI cartridge so you can flush the high TDS initial RO water after the unit has been sitting unused. This saves using up the DI faster.

 

[Shirak]

A DI canister lasts longer than 40 gallons of filtered water, right? I did nothing to the fittings except plug in the (blue) source water line to the "Step 1" canister connection and the (clear) output line to the Step 4 connection. The black waste line was already hooked up, and I did nothing to that.

I haven't run a system where TDS creep is an issue but I would think it should last longer unless your source water is very hard but it looks like it is around 88ppm

 

[Shirak]

Can you get a picture of the end of the RO filter where the two lines are? Maybe they got them backwards and the waste water is going to the DI

 

[Shirak]

My guess is they reversed them and your second reading of 90ppm is the waste line which should be the RO line and reading around 2-4ppm

 

[Dr. D]

I didn't realize the pump had an input... again no instructions. I assumed it did its magic behind the scenes somehow. So I understand that now. But the pump output seems "hard-wired," so to speak. It splits in two, with one line going to the pressure gauge and the other to Canister #3. I'm not sure if these pics will help much:

 

[dedragon]

they could have very easily messed up the lines so definitely check them.
I was talking about not rinsing a new ro membrane before running it through the di cannister

 

[Dr. D]

Here's the back:

 

[Shirak]

Ok so line water is going to canister 1 then 2 and then to pump which is split and going one line to pressure gauge and then RO In on canister 3.. So we are good up to that point

 

[Shirak]

Trying to figure out the other connections.. might be easier for you to follow them and see what's connected to what.
The Yellow is the RO water and should be around 4ppm and going to the DI cartridge filter 4. The red arrow is the waste line and should have tds higher than your source water. and going to your waste line flush system thingy

 

[Shirak]

This should be the RO line from the RO housing

 

[Shirak]

This TDS meter with the green arrow... is it number 2 that was reading 90ppm?

 

[Shirak]

I can't really make out the various connections below the RO housing.
Maybe there is something wonky with the auto flush system and waste water is somehow mixing with the RO water and getting sent to the DI cartridge.

 

[Dr. D]

First of all, thanks guys for such amazing help...

The yellow line

goes into the black thingy and then into canister #4.

The red arrow...

points to the black line in the picture below-- it is the waste line. The white connections on it make a loop to what I assume is the pressure flow knob, the silver knob at the top middle of the entire unit.

 

[Dr. D]

This TDS meter with the green arrow... is it number 2 that was reading 90ppm?

Yes, the green arrow points to the middle line to the TDS meter.