opinions on these 2 RO/DI units please!

Reef Water Reverse Osmosis RO DI Filter Aquarium 75GPD - eBay (item 110419805015 end time Aug-30-09 10:17:26 PDT)

Aquarium Water Quality: Pure-Flo II RO Units

thank you!

 

I would buy the first one--4 stage 75gpd is perfect--You want clear housings, and a verticle DI chamber.
The second one is just RO--I would pass.

 

This is mine--very similar to the first one--I have been extremely happy with it.
REEF AQUARIUM WATER FILTER 75GPD RO DI REVERSE OSMOSIS - eBay (item 250421440765 end time Sep-06-09 05:03:55 PDT)

 

I vote for the first one good unit! the one robman put a link to is also another good unit! cant go wrong with either of the two!

 

For around 150 you can get a 150 GPD unit which still only gives out about half of that a day. A 75 GPD unit will take you much longer to make water as you dont mind. My 150 GPD Spectrapure for $139.00 RODI makes 1 gallon in 20 mins.

 

HMMMM...1 gal=20 min...Thats 3 gal per hr x 24hrs..means your 150 is producing 72GPD!!!

 

The first one is the better of your first two. Coralife units have earned a bad reputation when it comes to quality control as well as water quality. They are mass produced in China or somewhere and use pretty low quality filters and components.
The H2O Science unit is also sold in the reef forums and online under their more common name or PurelyH2o.com . It is one of their Optima series units and is also a decent filter.

Personally I think you need to spend juts a bit more to get several things you will need and use like a handheld TDS meter, the inline pressure gauge the one unit includes, a bypass valve so you can take advantage of RO only water and not just RO/DI and most importantly a better quality carbon block. A 1 micron carbon block is good for about 7,000 to 9,000 total gallons of normally chlorinated water, this means 1400-1800 gallons of RO/DI and 5600 to 7200 gallons of waste at the normal 4:1 waste ratio. A 1 micron carbon is also not good at removing the chlorine portion of chloramines. If you spend a bit extra and get a 0.6 micron Matrikx+1 Chlorine Guzzler it will do 20,000 total gallons of water and is very effective and trihalomethanes and chloramine treated water.

A TDS meter is a must and handhelds are preferred over inline types since they are more accurate and give you portability to test not just two drdicated points but also your storage vessel, tap water, bottled wate retc. The pressure gauge along with the TDS meter is a very important troubleshooting tool as is the RO bypass valve for sampling.

Other units you may want too look at include the 75 GPD Premium from Buckeye Field Supply and others in the Optima series from H2o Science or PurelyH2o. Another good choice is the unit from Melevs Reef who is a saltwater hobbyist himself. I use and recommend the Spectrapure MaxCap myself but some feel the initial cost is out of their budget even though it is proven to save money from day one in replacement costs, water quality and filter life.

You should get close to the rated GPD from any RO or RO/DI provided you have sufficient water pressure and water temperature, thats between 50 and 65 psi at the tap and 77 degree water temp. Any lower and production drops and higher pressures are actually good. Buckeye Field Supply has an excellent calculator on their home page where you can plug pressures and temperatures in along with different membranes and come up with an accurate GPD. My membrane is rated at 75 GPD at 50 psi and I get over 110 GPD running it at 90 psi and better efficiency or rejection too at over 99%.

 

A TDS meter is a must and handhelds are preferred over inline types since they are more accurate.


Desert--I dont know how to cut that part of your post without quoting the whole thing. Help me on that if you would...Why are handhelds more accurate?? Just curious.

 

The inlines as they exist today are not truly temperature compensated. HM Digital manufactures the most popular models and their probes do not sense water temperature but in fact sense air temperature and as you know they are never the same. My RO/DI resides in my garage where it may reach 100 in the sumer months but Phoenix draws water from Lake Pleasant in the summer and it may be from one of the lower gates and at 58 degrees. The difference between 100 degrees and 58 degrees has a major effect on how accurate the TDS readings are.
I have seen the HM probes cut apart for display and the metal probe reading the temperature is located in the fatter portion of the probe right behind the little rectangular window or opening so it never touches the water stream.

The inlines also depend of water flowing past the probe, they cannot be dipped into a glass of water or reservoir with any degree of accuracy. Because of this you get two dedicated points only and to troubleshoot a RO/DI system you need a minimum of three TDS points or readings, Tap Water TDS, RO only TDS and final or RO/DI TDS. Since you only get two of the three you need two dual inline meters to accomplish what one handheld can do plus the handheld can do so much more. Being able to test the water in your topoff reservoir, or from both your tap and water softener, or from store bought Distilled or RO or the LFS, versatility is important.

I will also share with you, I ahve seen the working prototype or a new TDS inline probe that will be temperature compensated and its said to be very affordable too.

 

Thanks for the info!!!!