RO/DI performance (GPD etc)

Hi everyone. I have posted a few times and I am slowly aquiring everything to get my tank up and running. First I'll say I didnt realize how big these systems are, i didnt see the 10" statment on the canisters at first haha.

I just setup my RO/DI unit tonight and have a few questions.

First off this is the unit I bought from TheFilterGuys.

• clear 10" canister housings
• Stage One NSF rated 5 micron poly sediment filter
• Stage Two 5 Micron Matrikx NSF rated CTO/2 Workhorse carbon block
• Stage Three 0.6 Micron Matrikx NSF rated chlorine guzzler carbon block
• RO membrane 75 GPD Dow Filmtec
• Stage Five refillable cartridge with color-changing DI resin
• 100 PSI pressure gauge
• Auto shut-off (Requires Float Valve or Switch To Work)
• Membrane flush valve
• Dual TDS meter

Now the TDS so far is great, I have about 3 ppm coming out of the RO unit and 0 out of the DI. I haven't measured the tape TDS yet, ill re connect the TDS meter tomorrow to the tap water and see what it reads.

However I am currently running a test to see how long it takes to produce the pure water I should have some rough results in a couple hours I gather. That said It looks like there is quite a bit more waste water being produced then there is pure water. Is this common?

The second question I have is the water level in the DI unit only goes up about 2 inches from the bottom it never fills up fully. Yet it still producees pure water. Every once and awhile there is this surge where it completely emptys then it starts again and goes back up about 2 inches from the bottom and sits there. Shoudnt the DI unit completely fill up?

Third question is, can I run like a 30 foot tube from the DI output directly to the tank so I can just let it run for a couple days to completely fill up my 90 Gallon tank instead of bucketing it? My tank is about 25 ish feet and down 6 stairs from the RO unit which is in my laundry room.

 

*update*

TDS at tape is 154 ppm. TDS in to DI is 3, TDS out is 0.



I just did a quick calculation, 9 Liters in just under an hour. I rounded up to an hour so that is the equivilant of roughly 57 Gallons per day (24 hour period).

Thoughts on all this guys?

 

The normal waste ratio is 4:1, or 4 gallons, liters, whatever of waste for every 1 gallon, liter etc of good treated water. This is standard across the industry. With your relatively low tap water TDS you could buy a capillary tube type flow restrictor and trim it for 3:1 waste ratio but I would not go any lower or it will cause premature failure of the membrane due to lack of flushing which is what the waste does.

Its normal for the DI to only be partially full when in use, the water actualy flows up through the middle not around the outside like other filters.

Two things have a major effect on RO output or GPD, water pressure and water temperature. Your membrane is designed to produce 75 GPD at 50 psi pressure and 77 degrees F water temperature, colder water and/or lowers pressures produce less and higher pressures and temperatures (CAUTION- do not try to blend hot and coild water, this is the fastest way to ruin a membrane there is) produce more. Membranes can take pressures up to maybe 200 psi but anything over 113 degrees F wil damage them. If you want to increase production get a booster pump such as the Aquatec 8800. Time your waste ratio using a measuring cup and watch or clock. Time both the treated water then the waste water for the same period and compare the two, it should be very close to 4:1 waste to good, if not you may want an adjustable or capillary tube flow restrictor to get it where it needs to be. Colder water will waste more, this is normal but needs to be accounted for.

 

How about can I run a 20-30 foot tube from the DI directly to my tank which is up about 6 stairs. This way I can let it run without having to bucket it in .

 

Yes you can but most people recommend a top off container rather than plumbing directly to the sump or tank. That way if the float valve or solenoid/switch fails you only put a limited amount of fresh water in the system and reduce the chances of diluting the salt and a flood. Plumb it to a tank or vessel of some kind then have that feed the reef system.

 

oh yeah. No I will be bucketing it for standard water changes etc. This is to start the tank. My tank is empty and its going to take a couple days to fill. So I thought I would just run 30 feet of tube to the tank and let the RO fill it up. I just didnt know if this would have to much back preasure on the RO/DI to do it.

 

You'll be fine. You can figure about 4-5 psi pressure drop for every 10 vertical feet of lift (0.433 psi per ft) so it won't have much effect if you have sufficient pressure to begin with.

 

Great thanks for the info. This will be a lot easier to initially fill the tank. Ill just mix in the salt after the tank is mostly filled. Then put in the sand/live rock and top it off with salt water after.

I also ran the waste water of the RO to my Washing machine instead of wasting it I can use it to do laundry at least.

 

Just be careful to not overflow the washing machine, they only hold so much and your waste is 4 times more than the good flow. You make 10 gallons of treated water you have 40 gallons of waste.

 

Oh defintatley, I watch it then move it over to the laundry sink when it has enough water in it in. Not much else I can do. I will look in to the restrictor thing you were talking about. I believe it has one on it already, but I'll have to look at what it is exactly. Such a shame there is so much waste.