Is DI all it's cracked up to be?

Thanks everyone for the info!
OK, so I've seen in a couple places that lower GPD is actually better for cleaner water. So, assuming I go with Spectrapure, I could buy the refurbished 90 GPD model or I could go with the new 25 GPD model, for close to same price (Can get the refurbished 90 GPD for $128 + S&H, and could get the 25 GPD model for $149 + S&H). So, now my question is, should I go with the new lower GPD for a little more or go with the higher GPD, refurbished less expensive model (assuming that I can afford either)? With a 55 gallon tank, I don't forsee needing 90 GPD, but it's a better deal. So basically which GPD is better in my situation?

Thanks everyone!

 

0 tds is 0 tds no matter if its 10 gpd or 1000 gpd. I wouldn't worry about lower gpd, just make sure you service the unit properly.

 

Expect roughly the same rejection rates whether it be our 25gpd or 90gpd...Having more water on hand is better than not having enough.
FYI testing some of our 90gpd membranes, higher rejection have been achieved at spec, compared to the 25gpd units.

Shane,
SpectraPure, Inc.

 

You can't go wrong with Spectrapure and I just ordered the 90gpd waiting for the shipment

 

One thing to think of is with the 25gpd unit it will take almost an hour to make a gallon of water. If you do a 10% water change it will take over 5 hours to make 5.5 gallons of water. That's a lot of time when for the same money you could have a bigger faster unit.

 

Country1911 is right on. Spectrapures RO membranes are designed to produce their rated GPD at 60 psi and 77 degree water temperature, others can vary between 50 psi and 65 psi, still at 77 degrees. Chances are you do not have 60 psi or 77 degree water or both so you probably will not see the full 25 GPD, 60 GPD or 90 GPD or whatever so figure maybe 75% of the rated output. With a 25 GPD system that means it would take a full 24 hours to produce maybe 18 gallons of RO/DI water but with a 90 GPD you would have around 70 gallons in that same period of time. The rejection rate or removal efficiency (RO TDS) will be the same either way.

What you have seen is you do not want to buy a system with a 100 GPD Dow Filmtec membrane since it is only a 90% rejection rate nano filter designed for pool and spa use, not a 96-98% rejection rate RO membrane. Spectrapure takes that 96-98% rejction rate membrane and improves it even further by treating it with a special proprietary process then testing it for quality control unlike any other vendor or manufacturer.

I am not in Nevada but in the Phoenix area and have been a certified water and wasterwater treatment professional for over 37 years. I have no connection to any vendor or manufacturer so just speak from experience, both good and bad.

 

I have a Aquafx filter and it's 000 tds output from 170 tds water. Works awesome.

 

ANY RO/DI should produce 0 TDS water, at least for a little while. The true test of a system is what is the RO rejection rate (RO only TDS) and how long will the RO/DI TDS remain at 0. Thats where Spectrapure with their specially treated membranes and more than that their custom blended DI resins come out on top every time regardless of who the competitor is. Longer life equals lower cost of operation and ownership.

 

^ the MAN when it comes to RO/DI systems. His posts are the reason I went with spectrapure and couldn't be happier.

I actually see 85-90gpd with my 90gpd unit. I have roughly 65-70psi and 55-60 degree water tho. My RO membrane routinely gives 001tds from >100tds.

 

I'm sold - I put in the order for the Spectrapure 90 GPD unit!
Thanks for all the input and great info everyone!