tds and ro

Dont know if this is the right forum but here we go.. OK just got my tds meter. My tap water reads 720. Just replaced all my ro filters and its reading about 90. I have a 4 stage ro atm. Will adding on a di get it to zero? Should I try to find a company thats selling zero tds water lol. Not sure if it is actually that big of a deal to get it to zero or not. I tested the ro water and I get zero phosphates and trates. I dont really have a algae prob except with red turf algae. Dont really want to buy a new ro but if I need to I will but a ro/di 6 stage or better lol. Just looking for some advice I guess=) thanks.

 

Just buy an add-on DI stage canister, that should lower your TDS down to 10ppm or lower. With tap as high as 720, you may need dual DI stage to get it down to 0.
http://filterdirect.com/product_info.php?products_id=85

 

Thanks for the link) thats even cheaper than the ones I found on e-bay. I went down the street to the water place, was actually surprised there water tested at 8 tds and 30 cents a gallon is not too bad. So I think I will buy that di add on and if I cant get it lower than 10 I think I will just use the ro I have for drinking water. And buy my wc top off water=)

 

You should be able to get zero even without DI. How are your other stages? Are all your filters new?

 

Also have you calibrated your TDS meter?

 

All my filters are new just replaced everything including membrane. Tds meter is brand new factory calibrated. Borrowed my buddys (plumber) tds meter read the same as mine. Dont know what you mean by how are my other stages? Just borrowed my buddys local reefers tds he just got in saturday it was calibrated with NaCl from the manufacturer and its reading were wayy different lol. It said city water was 490 and my ro was 33. Soo lol dont know which to believe now..

 

Prefilters and carbons have very little to absolutely no effect on final TDS. they are there to protect the RO membrane which is the workhorse.
Which membrane and replacements did you buy? There can be a big difference in membranes and the quality of replacement filters is all over the spectrum, some doing a good job of protecting the membrane while others are comparable to a screen door.

Don't add DI until you get the RO TDS problem figured out. You will eat DI resin like there is no tomorrow. First thing is let it run to waste at least 5 gallons before testing to flush the antimicrobial solution from the membrane then test again after that long continous run.

Where and how are you testing the TDS and in what kind of container? Use a squeaky clean clear glass drinking water glass with no soap residue or water spots, hand wash it if it has been in a dishwasher. Make sure to rinse the TDS meter and glass in distilled or DI water between each test and after use. let the readings stabilize for a minute or two.

If the TDS is still high you might try reseating the membrane in the housing, it goes in further than you think and could be bypassing. Does the GPD and waste seem right compared to what you had before?

Someone stated you could get 0 TDS with RO only, thats not possible since a RO is not an absolute barrier but you should be in the 96-98% removal range. To give you an idea, my tap water TDS is 830 and I get down to 5 with RO only and a true 0 TDS after DI so you have something going on.

 

I just pay my plumber buddy 40 bucks and he replaces everything so not sure whats in there exactly=) Yea I tested after about 7-10 gallons were used from it. I was testing it in a small glass cup I did rinse it out first. Did not know to wash the meter off with distilled after test tho. I will try resetting the membrane but yea it is about the same as before. Wow I wish I could get down to 5 tds with just ro lol how many stages you have on yours? I am about to build me a ro hook it up right to the softner and try to run 5-6 stages with di but if I could get this sucker to get down in tds I wont have to lol. Been about 3-4 days since everything was replaced and im running 100 tds already and it will stay at 100 for a couple months then up up up and away it will go lol=( Wish I knew what was going on, my plumber buddy who knows nothing about tds for reef tanks thinks 100 tds is great after tap being so high hehe.. Thanks for the replys.

 

You really need to find out what membrane and filters he used , you may have got hosed.
Do not get hung up on "STAGES". This word is a ploy used bt ebay vendors to make cheap low quality drinking water systems sound like the best thing since sliced bread. You can get 99+% rejection with two stages if you want, actually one will do it for awhile anyway. Never buy because its 6 stages instead or 4 or 5. Always look at what those stages contain not how many there are.
I have 1 prefilter, 1 carbon block, 1 RO membrane and 2 DI filters. My unit is a Spectrapure MaxCap UHE and is quite expensive initially but as you can see the water quality it produces is superior to about anything and the cost savings I have realized in DI resin alone has already returned almost 1/4 of my investment in the first year of use alone.

The typical, what I would call ebay quality RO/DI unit uses very low quality filters in high micron or even unknown micron ratings so they depend on multiple barriers or filters to accomplish what a better unit does with just a few filters. An example is a 10 micron prefilter, a granular carbon filter followed by a 5 or 10 micron carbon block the into a 100 GPD 90% efficient membrane and follwed by one or two very small horizontal DI filters. The problems with this arrangement are several. One is a high micron prefilter passes particulates and colloidal material on the the carbon which renders it useless. Carbon is made up of billions of tiny microscopic pores so needs to be clean to work or it does not adsorb chlorine and VOCs. Next, granular carbon products have a tiny amount of surface area and pores in relation to a good carbon block, on the order of 300 total gallons of chlorinated water compared to up to 20,000 gallons of chlorinated watre with a good block. Its spent after the first 60 gallons of RO/DI since you waste 4:1 and the other 240 gallons goes down the drain. remember all water including waste passes through the prefilter and carbon.
Next the second carbon block gets plugged up by the fines or dust that is produced as the soft granular carbon in front of it breaks down and wear away. Big problem since now you are sending chlorine to the RO membrane and dissolving it away to nothing. Finally the tiny little horizontal DI housings usually only hold 6 to 9 oz of DI resin and since they lay on their side the watre short circuits or channels along the bottom and the resin at the top never gets used. Poor design.

Now lets compore this to a better unit, stil not the cadillac but at least a chevy. You start with a prefilter rated at 1 micron so it traps almost everything and allows the carbon to do the job it was intended for and does not have to act as a secondary prefilter. Next you use a single 0.6 micron carbon block. This carbon does not get so many solids passed to it so it will last closer to the 20,000 gallons of water it is rated for. Thats 4,000 gallons of RO/DI and 16,000 gallons of waste not 60 gallons of RO/DI and 240 gallons of waste. Big difference! See where I am going here? All it takes is a single carbon block to outperform what most try to pass off as "satges" to impress you. Next they use a 75 GPD 96-98% rejection rate or efficient RO membrane instead of the 100 GPD 90% efficient one. Monsterous difference here! 6 to 8% difference does not sound like much but there is a very accurate rule of thumb with RO/DI systems. it goes like this; For every 2% you increase the RO membranes efficiency you DOUBLE the life of your DI resin. Thats very important. Only 2% doubles you effective life of the DI so imagine wehat a 6 to 8% increase in efficiency does for you. Wouldn't you like to have DI resin last 4 or 5 times longer at $10-$20 a pop?

It ends up being a pay me now or pay me later proposition. Spend more on a good system or good replacements and save from day one or spend less up front and pay more from day one. The savings very soon catch up with you and you soon have much more invested especially if you keep the unit for long or make much water.

 

Wow, thank you for your help im gonna have to read this more than once lol. I think im gonna have to just start knowing whats going in my ro etc.. I need some more education on this so google will be my friend for awhile=) Thanks for the help.. Also im sure my tank will be thankfull to=p