Question about RO/DI

S

Samcorp

New member
Hi everyone. I just hooked up my RO/DI Maximma Kent Marine and I am now getting around 25-29 PPM. Is this good? My water (I tested using a digital TDS/Temp meter) is 180 PPM.

Will 25-29 PPM get me a lot of algae or is it pretty good? I will also be running a phosban reactor in my 90 gallon reef.

Thanks,


Sam
 
That is still pretty high. Even an average RO membrane rated at 90% rejection would drop your TDS down to around 18, then the DI resin would bring it down to 0.

Is the unit new?

Couple of things that could cause this;
the unit is hooked up wrong
the RO membrane isn't seated all the way,
the RO membrane is defective

Is it possible to get a picture of how it is set up, or at least describe it.

Sure 25-29 is better then 180, but should be getting 0, and you have no idea what is making up that 25-29.
 
Don't have any pictures, but the membrane (small white cartridge) is on the top. The rest of it looks like the picture on this site:
http://www.marinedepot.com/ps_ViewI...osis-Saltwater_Aquarium_Supplies~vendor~.html

Question though. This product did not come with a manual (bought it used) but the guy said he put a new 75 GPD membrane in it. The DI is about 50% used according to east coast aquatics in PA and I had to buy a faucet adaptor. However, I do not know which tube is the product water and which tube is the waste, because the tubes are different colors from the manual. However, from looking at it, it seems that the product is the "blue tube" I am using right now. Also, I found that there is more waste water in ratio to product water, so after looking at what I think is the waste tube, the waste is producing more water in comparison to what I think is the product tube. Is this correct? I'm going to check the TDS of the waste tube now to be sure.
 
Good news, I know the tubing is right because the waste tube is giving me around 270 PPM and now THE RODI WATER IS ONLY 19-20 PPM!!

I think the issue was some of the water left in the RO/DI when I bought it may have gotten into this mixture which caused it (in about 2 gallons of water) to be 25-29 PPM, plus it was somewhat inconsistant. Maybe dust affected it too? I put a cover on the salt bucket that was given to me, which serves 170 gallons of water (looks like your average salt bucket). I put a cover on after I checked the water (when it was 25-29 PPM) and now its consistent with 19-20 PPM whenever I move the TDS meter around.


Is 19-20 PPM acceptable? The guy did tell me that I might need to replace the "carbon block (I think thats what it was callled)" later but for now it should be okay.

Could that be causing the issue? Or am I probably right that the left over water could have caused the higher amount of PPM?
 
Edit: I forgot to talk about the left over water: There was some left over water in the RO/DI which the guy told me I needed to leave in there because the membrane and other cartridges cannot be dried out. I think maybe a VERY TINY AMOUNT of that left over water got into my RO/DI mix because although I tested the ro/di in the sink first its always possible some water wasn't used, since RO/dI produces very slowly. What I will do now to test if I am right or not is put the RO/DI water in a cup (new ro/di water) and test the TDS. I hope I am right.
EDIT: I TESTED IT, the PPM IS STILL 20 in the CUP. Ignore this portion of the message.

One more thing: regarding the bucket of salt (serves 170 gallons) how much water can that hold? I think its 5 gallons, but I am not 100% sure. And the hydrometer, how is that used? Do I fill it with water then take it out to check the salinity? I want around 1.027, correct? Or should I follow the hydrometer as the green numbers are 1.020-1.025?
 
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Also, does the amount of water I am pushing into the RO/DI matter? I put the faucet on full blast so that the pressure would be stronger (I live in a house in suburbs)

And does the temperature of the water matter? I want to put the heat a little higher so that I don't have to heat as much when I put some of it in the tank. The heat will always, however, be below 80 degrees when I use the faucet to heat it.
 
Theres a blue valve imbetween the tap water in tube and the tube that actually goes into the RO/DI. It seems that at this point the valve is fully open, therefore letting all the water in. Maybe too much water is being pushed in at once, causing less filtration? Should I put this valve at maybe 1/2 the amount, so that less water goes in at once? Or is this not true since the waste water will displace the same amount of water each time?
 
You really should be getting 0 TDS at the output of your DI stage. Testing this in a clean glass is a great idea, your other container(s) may have a lot of residual stuff giving you a higher reading. Anything more than 0 TDS means you either need to replace some or all of the filters (except the RO membrane which you said was new). If you can, check the TDS of the water at the RO output. It should be no more than 2 to 5 there after running for about five minutes or so. If it's significantly higher than that, something before the RO membrane is amiss. If the DI stage is truly in good condition, it should take the 2 to 5 from the RO stage down to 0.

Pressure and temperature definitely affect RO/DI system performance. IIRC most manufacturers recommend up to 80 psi at the input and 70 degrees F for water temp. If these parameters are lower, your output will be slower than rated and your waste water to pure water ratio will also change.
 
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Keep the feed valve fully open for maximum pressure and I suspect your bucket is making the water look bluish. The wate should be clear as a bell in a glass container, if it's still bluish in a glass, investigate.
 
I put the water into the glass. Its not bluish anymore, its just the bucket.

Also, my parents told me that they're pretty sure warmer water has more TDS so I put the water into a colder range. I'll try to go for 70 degrees. I don't know about the PSI of my water but I just turned the faucet about half way down instead of full blast. Hopefully that will help.

If nothing works I really do not have any more time to mess with the RO/DI and change cartridges and etc. I guess I will have to stay with 20 PPM. At 15-20 PPM, is this really bad? Could I still do a reef with this PPM? I'm not saying its guaranteed 15-20 PPM as I hope it will go lower. But if I am going to be at 15-20 PPM, what could happen?
 
Sorry this is a little off topic but does live rock ALONE with simply salt water require a heater? The person who sold me the live rock at east coast aquatics gave me the rock just moist in a bag, without water (I only bought about 1/4 a lb just to see whats on the rock). I am putting the rock into the salt mix but I do not know if a heater is necessary.
 
Curious, how are you regulating the input water temperature? Do you have the input hooked up the the hot water tap instead of cold water? If so, switch it to the cold water tap.... unless you have a tankless hot water heater. Hot water tanks have metal rods in them to help prevent corrosion, but you don't want that kind of stuff going into your RO/DI.

I'd recommend leaving the tap fully open, not halfway. You won't be reducing the pressure that much by doing this, you'll only be reducing the flow capacity to your system.

Any level of TDS is an unkown you are putting into your tank. Hard to say what will happen, but nuisance algae could be a problem. You might want to get another TDS meter to verify your readings as well. Many RO/DI units come with Dual TDS meters which monitor the RO membrane output and the DI stage output. Could be that the TDS meter you're using is out of calibration.
 
Well the TDS meter can check temperature too, which seems pretty accurate. I'll turn on the tap on full blast now. I am now using cold water instead of moderately warm and it says on the TDS meter that is it "has been factory calibrated to a NACI 342 PPM Solution. For more information on calibration, visit [this website]"
 
I just checked the TDS with a bit colder water. It is lower now, 18 PPM. But for some reason the temperature of the RO/DI water is warmer (78.8 degrees) than the waste water, which I assume is because the house is 80 degrees and the RO/DI cartridges were warmer from before. Once the temperature goes down I hope the TDS keep goes down too.


Also: I noticed that the DI Resin (I'm pretty sure) is only about 60% full of water. Is this supposed to happen? There does seem to be water going through it.
 
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Just and only use the cold water tap -- using any warm water could harm the RO membrane -- sure it will feel okay to you, but there could be a spike, better to be on the safe side. And like Mike said, most water heaters are going to have way too much "stuff" in there which will foul up your prefilters too.

It is fine that DI chamber is only half-way full.

You should test the TDS of the water right after the RO membrane, but before the DI resin -- should give us an idea if the RO membrane is still good or not.
 
How do I test the TDS of the water right after the RO? Also, I am mixing salt water for my first time; not having too much luck. I just followed the directions (1 lb per 4 gallons of water) and I don't know exactly what a pound is but I just mixed 2 cups of salt instead. Then I put it in 4-6 gallons of water and put a hydrometer in it (this water is in a 14 gallon sump) but the hydrometer isn't even detecting a salinity level. Is the hydrometer broken? The arrow is pointing down as if nothing was in it.

Or should I just keep adding salt and messing around with it until it works?
 
This is the type of hydrometer I have:
sea_test_hydrometer.gif
 
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