RO add on kit question

Hi guys I'm new to the forum and have a few questions regarding my setup for drinking purposes (no DI). So here it goes...I have a 5 stage RO unit for the last 1 year. Tap TDS is ~225ppm and the product is 7ppm running at a 3.58/1 ration. Tap pressure is abnormally high at 90-95 psi so I figured I could take advantage of it and add a second membrane to improve efficiency without adding a booster pump. I'm currently running a untested 90 gpd Filmtec with a 5 micron sediment and (2) 5 micron carbon block filters. Just 2 weeks ago I was due for my first yearly filter change (TDS shot up to 15ppm) and noticed some blackish residue in the first three stages, I thought it may be algae. So I decided to look further into it and discovered that the pre-filters that came with my setup are poopoo!! SO.....I bought a 0.2 micron ZetaZorb, 1 micron carbon block, 0.5 micron carbon block, and a RO add on kit with the spectraselect 90 gpd membrane.

My question is...which RO membrane do I put as the first membrane? The older (1yr old, untested, ~96.8% efficiency) membrane feeding waste water to the new tested membrane?? Or the other way around??

I'm still waiting on everything to arrive so any suggestions or comments are welcome!! I also ordered 2 pressure gauges, DM-1 dual TDS meter, flow restrictor, and several elbow fittings.

 

Dual membranes do not improve the efficiency or cut down on the waste as some may try to tell you. They do increase the GPD though which for some with larger tanks and lots of water needs is a good thing. I had a Spectrapure dual membrane 180 GPD MaxCap myself for several years and loved it but really didn't need that much water that fast once I installed an ATO storage reservoir. When I was making water manually it was nice though as I didn't have to standa around as long waiting for water.

You made a great choice with the 0.2 ZetaZorb sediment filter, I use the same myself and its fantastic. I would spend a few minutes though and do a little plumbing change with what you have and you will have a better system and DI also for a very minimal investment.

You have two carbon blocks which is totally unnecessary, notice Spectrapure does not sell systems like that? Two carbons is a very old school design going back 25 years ago when we didn't have the carbon blocks we have today so it took two carbons to last 6 months, if that long, and your membrane did not melt from the chlorine. With todays 1.0, 0.6 or 0.5 micron extruded carbon blocks you can get 12,000 to 20,000 total gallons of chlorine removal with a single block as long as it is protected by a high quality low micron sediment filter such as you now have. Old GAC carbons lasted 300 total gallons on average, thats 60 treated gallons and 240 waste gallons at the normal 4:1 waste ratio versus todays 2,400 to 4,000 gallons per carbon block, huge difference.
Two carbon also adds additional headloss before the RO membrane so reduces the membrane rejection rate and you DI is exhausted faster.

You can easily remove the 1.0 micron carbon block, move the 0.5 carbon in to the middle position then replumb the empty third canister in to a vertical refillable DI with 15 minutes time and maybe $5 in parts if you don't already have them and a new $20 SilicaBuster DI cartridge. Its as simple as removing the canister lids from the top bracket, unscrewing the nylon nipple connecting the last two together, moving the compression or speed fitting from the last one to the middle one and having it lead up to the RO membrane like it used to do from the third one. Now you have sediment, carbon block, RO membrane and empty housing. Next you rotate that empty lid/canister 90 degrees so the IN and OUT face back to front rather than side to side, take the RO treated water line back down to the IN of the third canister and the OUT is your treated RO/DI water. If you still use it for drinking water you can separate the RO drinking water pressure tank from the DI filter with a check valve as pictured here so the DI comes straight from the membrane and not the pressure tank so TDS creep is not an issue:
http://spectrapure.com/huds/4-STAGE-DWK-RODI-NAG.pdf

Unless you have a need for 180+/- GPD of RO/DI I would not add the second membrane, all it does is get you more water faster, it does not cut waste or improve the rejection rate. You still maintain 4:1 waste ratio since the second membrane is receiving the concentrated brine from the first membrane so will be 25% or so higher TDS than your tap water was to begin with so it is doubly important you keep the ratio up to flush it while in use and since the second membrane is treated this higher TDS the rejection rate will not go down, it may possibly go up just slightly.

Wish you would have asked these question before ordering, I would suggest you return the inline TDS meter also as it is not as accurate as their $25 handheld and it is limited to two places while the handheld can be used anywhere. I have two dual inlines and never even turn them on as they never agree with the COM-100 handheld since they are not temperature compensated. if you return the membrane and the TDS meter you can get a SilicaBuster DI cartridge and a TDS-3 or TDS-4TM handheld meter for about the same money and get some value out of them.

Also since you noticed the original filters were yucky, did you disinfect the system before installing the new replacements to sanitize it? This is very important and it is recommended at least annually but I do it every filter change or 6 months to be safe and it only takes a couple minutes since you already have the housings empty.

 

Thank you AZ for responding! Ill try to be to the point and answer everything paragraph by paragraph...

"Dual membranes do not improve the efficiency or cut down on the waste as some may try to tell you."

I was under the impression that 2 membranes hooked up in series would produce more product water with the same 4:1 waste ratio...man I'm confused.

"You have two carbon blocks which is totally unnecessary"

Yes most likely, but my wife and I detected chlorine on two separate occasions in the past year. After going through "junk mail" I found an envelope from my water company stating they detected Giardia in one of several public wells that supply the area and that they will be adding chlorine to the system to rid it of bugs. So after researching the web I couldn't find much info about others with an RO system on a public well getting shocked with chlorine. Please correct me if I'm wrong...I was thinking of going with an extra carbon block (1 micron to not lower the head pressure as much as a 0.5 would) to safe guard against the occasional chlorine shock treatment. Do I have a valid...theory?? Maybe just use Spectrapure's 0.5 chloramine carbon block?

"You can easily remove the 1.0 micron carbon block, move the 0.5 carbon in to the middle position then replumb the empty third canister in to a vertical refillable DI"

I only use my system for drinking water. Is RO/DI water ok to consume on a daily basis?

"Also since you noticed the original filters were yucky, did you disinfect the system before installing the new replacements to sanitize it?"

Well....no not yet. I have 2 questions here:

1) I hate using chlorox to disinfect things. It seems to take a while to get the smell and taste out of what ever you put it on. There is another disinfectant I was thinking of using called Star San. It only takes 1 minute of contact time to kill everything without imparting any flavor or smell. I use this stuff to sanitize my brewing equipment and I like it way better than bleach. Any cons to using this as its main active ingredient is phosphorus? If phosphoric acid comes in contact with the membrane will it do anything adverse?
2) Should I be concerned with biofouling? I've read a thread where someone with a biofouled membrane was advised to run hydrogen peroxide through the 3 empty canisters and let the membrane soak for 30 minutes? Is this something I should do too? My TDS jumped from 7ppm to 15ppm and that's when I changed all the filters except the RO. Its currently back to 7ppm after the filter (5 micron) change, so im not sure if I should leave the membrane alone or flush it with peroxide or just change the damn thing out!

I have not installed the better filters or extra RO membrane yet. My system came with a extra set of crap filters that I'm using for the past 1-2 weeks until everything gets here.

Thank you for the advice! ;D

 

I never understood this "bypass DI for drinking" thing. It is a scientific fact that pure water is not optimal for the body. (Not optimal doesn't equal harmful. See my post in the "is RO water safe" topic on water toxicity. Bottom line is, if you go on a three day fast and do not take any other nourishment but copious amounts of pure water, you will very likely die or end up in intensive care. If you eat and live normally, just replace tap water with DI water, you will be perfectly okay.)
However, there are two reasons bypassing DI is stupid.
- reason 1: RO water is already missing above 95% of all the stuff in tap water. Skipping the DI for nutritional purposes is like saying that even though you are a vegetarian, each day you'll eat a single milligram of beefsteak for animal proteins. It's absurd.
- reason 2: your corals need a LOT more minerals and salts in their water than you. Still, you don't give them tap water. You give them DI water, mixed with salts, to produce optimal sea water. For yourself, it's the same. If you want optimal fresh water, there are postprocessing cartridges you can buy for your filter, for exactly that purpose. That way you get 0 contaminants, and all the salts your body would expect of water (once again, if you have a balanced diet, RODI water is percectly fine, ...except during heavy workouts or heavy sweating, in which case you should prefer isotonic drinks even to tap water.)
- reason +1: if you just want your resin to last longer... Really? I mean it's not THAT expensive... Come on! Don't be that cheap. The bypass kit will probably cost more than you would save over two years.

 

Dual membranes increase the gallon per day but the waste ratio should remain at 4:1 for proper membrane flushing ie 90GPD at 4:1 ratio = 90G treated and 360G waste, 180GPD at 4:1 = 180G treated and 720 waste. Still 4:1 but twice as much of both treated and waste. If you need water fast this is the way to go but who needs 180 gallons or RO every day or 7.5 gallons per hour versus 90 gallons per day or 3.75 gallons per hour?

When I had my drinking water and reef water coming from the same system in years past I first installed a second 5G pressure tank to have more pressurized water for drinking then later upgraded that to a 14G pressure tank to store the RO. I separated the RO from the DI like in the drawing I attached before so the pressure tank stored RO only but I could also make DI straight from the membrane bypassing the holding tank.

A single 0.5 micron carbon block will remove 99.9% of the chlorine or chlorine portion of chloramines flowing at a much greater velocity than will be travelling through the RO system, it does not take much contact time at all. Probably the reason you detected chlorine before was the sediment filter at the time was relatively coarse and the pores in the carbon were fouled so you experienced chlorine breakthru. With the ZetaZorb you will not have this problem and the carbon will be able to adsorb its full capacity of chlorine before ehxaustion.

Yes RO/DI is safe to consume. The WHO has been trying to disprove this for decades but the fact is we do not receive our minerals from drinking water, its in the food we eat. Eat a sensible diet and drink whatever you want. I do not recommend RO/DI for drinking though as it has a very blah or bland taste and is not refreshing to the palate. This is the reason I attached the drawing showing how to separate the DI from the RO drinking water tank with the tee and check valve. In this way you still have pressurized RO only for drinking, icemaker, pet watering etc. but still can make DI water directly from the RO membrane, bypassing the pressure tank and its TDS creep problems. This has been done for decades and I did it myself for decades as I described above. It made it very easy to justify my first RO/DI purchase and saves you a mint on bottled drinking water and on buying distilled or RO/DI for your reef tanks.

Make sure you disinfect the system before installing the new filters. I have posted the process hundreds of time but basically all it takes is two spoons or caps of Clorox and 5 minutes time. The reason you have problems getting the chlorine smell to go away is like most of us, you use too much bleach. Fresh Clorox or unscented household bleach contains 50,000 ppm of chlorine, thats very strong. Even if it has been sittin garound it is fairly stable and is probably still 30,000 ppm or 3% chlorine. It does not take much to disinfect things so two cap fulls in the first canister is all, more is NOT better in this case. The Centers for Disease Control in Atlanta says 0.5 ppm of chlorine of 1/2 of a part per million will kill 99+% of everything with a contact time of 1 minute. Thats a very weak solution and 2 capfulls is much greater thanm that when you consider the volume of two or three canisters.

I use Star San, PBW and Iodophor myself in my homebrewing hobby too but bleach is fine for the RO canisters if used in moderation as described. A funny story is my reef hobby got me into homebrewing believe it or not. I needed to get a CO2 bottle filled for my calcium reactor on my reef and someone suggested the local home brew shop since they were close and filled CO2 while you waited. To make a long story short I walked out with a full bottle plus the $100 DIY brewing and bottling kit and in the last 10 years it has gotten out of hand with a 4 keg chest freezer and more!

sigmoid, the cost to bypass the DI is about $5-$7. Its as simple as a 1/4" John Guest tee and a 1/4" check valve and 3 minutes to cut the line and install it. Take a look at the drawing I linked to before.

 

I think the whole WHO ordeal about minerals in the water is about "public health", which is a lot more complex than personal health...
The thing is, based on statistical research, they proved that if the public water supply contains this and that in such and such concentration, then the case numbers of certain chronic diseases will drop over millions of people. Say, you put fluoride in the water, less cavities. Etc.
The reason for this is mainly the poorer segment of the population, who do not have access to a varied, healthy diet, and there even a little of those minerals is better than, possibly, none.
If you can afford a RODI system, I think you don't need to worry about that sort of thing.

 

They never even mentioned the minerals in the water are inorganic and cannot be assimilated by the human body which needs organic supplements from solid food. Their whole study is bogus.

 

Last night I sanitized the system and added a new ZetaZorb followed by 0.5 micron carbon block filter. When I removed the membrane I noticed it had a brown/reddish residue on it. So I did a little research and found someone with similar issues. He was advised by a Spectrapure tech to use hydrogen peroxide under pressure to clean the membrane. I have to say my system is working night and day better.

TDS from tap: ~210 ppm

TDS with a new 5 micron sediment, (2) 5 micron carbon blocks, 1yr old bio fouled membrane: 7-9 ppm (it shot up to 15 ppm with the old filters)

TDS with a new 0.2 micron ZetaZorb, (1) 0.5 micron carbon block, same membrane as above flushed with hydrogen peroxide: 2 ppm!!!

Anyone interested in how to clean a bio fouled membrane here is the link: Anaerobic smell from RODI - Page 2 - Reef Central Online Community Archives

Thanks again AZ, I would never use anything else other than ZetaZorb, keeps everything clean and flowing, just the way I like it 0

 

Glad I could help.
Your rejection rate or removal efficiency was 92% with the old filters, 95% with the 5 micron variety and now it is 99% and with the improved sediment and carbon block filters you should not have the fouling issues anymore. If you had DI the resin life would probably quadruple or more with that 7% improvement in rejection rate.

 

Its a vast improvement There is something about the word resin and my drinking water that rubs me the wrong way, no science behind it, just how I feel. I'm pretty happy with having a TDS of 2 ppm, unless you can convince me otherwise :thumb_up: