small RO/DI system???

so let's start out by saying i know NOTHING about this subject, other than the fact that every week i'm going to my LFS and buying 15gal of pre-mixed RO/DI water.
also, i've only been keeping SW for around 6 months(FW my whole life)

i'm looking into buing a ro/di system, but from what i'm seeing is they range quite a bit, like making 75gal/day.
well, all i really need is one that can do 15gal in a day or two. even if it takes a week to do 15 gal, that's fine too.
is there anything that small? because i apparently don't know where to look or what to look for.

also, like i said, i know NOTHING. what all do u have to aquire, and what all do u have to do to set up one of these systems?

ANY help would be appreciated!

 

You won't find one that small to my knowledge (maybe 50 gpd). to my knowledge, you get about 4-5 gallons of waste per one gallon of clean water, so at that rate, to get 15 gpd of usable water, you will waste 60 gallons, totalling 75 gpd. A 75 gpd is a reasonable choice for you it would seem.

 

Unless cabinet space or storage area is a problem a 75 or 90gpd model would be a good choice.The standard size filters and di would work better and last longer than any compact size.

 

I have 50gpd ro/di and it makes plenty of water. I upgraded all the filters a di resin when I got it though. I've been using aquafx and have been pretty happy. The system hooks up easy. I installed mine in the spare bathroom and hooked it up to the sink and the waste drains into the tub.

 

I've been looking into this as well. I heard DI is when it starts getting expensive. Do you need RO/DI if it's a FOWLR set up?

 

Di isn't expensive at all. That's what makes it pure. I replace my di for 30 bucks every few months or when I show and tds.

 

I got my RO/DI unit from Spectrapure. It was a Refurbished unit.

Here is the link.
http://spectrapure.com/FACTORY-REFURBISHED/Refurbished-90-GPD-RODI-System
It makes about 10 gallons of RO/DI water in 3 hrs. I have had no issues with this unit at all. Just be sure to buy a RO/DI shutoff valve and a float switch. I have flooded my back room 3 times until I got one. lol I had a bad case of "Wife Rage" after that.

 

Just because the system is rated for 75 or 90 GPD doesn't mean you need to make that much, it will just make water faster. I can tell you, you do not want a 15 or 25 GPD system, that means it takes a full 24+ hours under perfect conditions to make 15-25 gallons going drip drip drip at less than 1 gallon per hour so your faucet is tied up all day and night. The 75 or 90 will make 3 gallons and hour so you can make your 15 gallons in about 5 hours, one evening.

The Spectrapure would be my choice, in fact I use only Spectrapure myself after owning 6 different RO and RO/DI systems over the last 20 years.

 

Correct me if I'm wrong (because I don't know for certain) Isn't the gallon per day determined by the membrane? Like if you buy a 50gpd system and put a 100gpd membrane in it then it will be 100gpd?

 

Yes, the RO membrane is what determines the GPD, they commonly vary between 15 GPD and 150 GPD but there are some not well suited for the reef hobby since they have poor rejection rates or removal efficiencies. Some are better suited for drinking water where TDS isn't so much an issue. TDS is what makes the water taste good but it eats DI resin in a reef RO/DI. The most common membrane used in reef RO/DI systems is the Dow Filmtec 75 GPD. The Spectrapure systems start with a Dow 75 but they go a few steps further by specially treating the membranes with a proprietary process to improve their performance then either batch or individually hand testing them for quality control. Most vendors use dry off the shelf untreated and untested membranes so you get what you get with no guarantees. Luck of the draw.