RO Unit newb questions

[likwid]

Hey guys,

I am looking at getting a RO/DI unit for the tank I am about to buy, and have a couple quick questions. The tank is only 30 gallons, so I do not need a large unit.

I have a hose hookup in my garage, and would like to use that for the unit. My question is, a lot of these units are 100 GPD. I have no idea how these units work, do I just hook it up to my garden hose pipe and turn it on and let it do its thing? If I only want to make enough to fill a 4 gallon jug and no more, how do I do this?

Thanks

[Ryan_Lap]

Just hook up the unit. Check to see if your getting the right tds. Then fill your 4 gallon jug. Turn the water off.

[likwid]

How long does it take to fill a 4g jug? Do I have to sit there and wait for it to do so? What unit do you guys recommend for a small tank?

[Ryan_Lap]

Well if its 100gpd just take 100 divide by 24 hours in a day. Thats 4.16 gallons an hour on average. If its 50gpd then it would be about 2gph.

You could also hook the ro unit up to a barrel or brute trash can and have a float valve in it that so you dont have to watch the container. Youll always have a bunch of water on hand then.

[Oceanic]

Make sure to waist the first 2 hours of water if the unit is brand new, the filters are preserved with an antimicrobial agent that should not make it into your tank water.

:mrgreen:

[likwid]

Does the unit require constant water flow from the tap for the entire time while it is doing its thing? If so, how much are you guys paying extra for water each month?

[Ryan_Lap]

Well if you have the ro hooked up to a float valve in the barrel, it will only turn on the water when its making ro water. It doesnt constantly run.

[mark]

Assuming your garage is heated or at least not worried about freezing.

Could run off hose but think about teeing in before tap so could just leave hooked up. Also the idea of a storage container with a float is good. I'm just using a trash can with a bulkhead near the top that goes to a drain if I forget so it doesn't go all over the basement.

Don't expect anything near 100gpd from a 100gpd unit though. From Aqua-safe's site the ratings are for 77°F, 65psi and 200 TDS and the output goes down 1.6% for every 1°F

[Myka]

You can just turn it on, fill up your jug, and then turn it off.

As well as dumping the first 2 hours of water on the brand new cartridges, dump the first litre every time you start it up. Don't forget to buy a TDS meter at the same time. Buying an RO with a TDS meter is like buying salt without a hydrometer (or refractometer).

[likwid]

Thanks for all the help guys! Anyone know of someone selling one for a good price, or a site to get a smaller one for cheap?

[Myka]

They're all the same size, except they have a different number of stages. So a 2 stage would be smaller than a 4 stage. Make sure you buy a 4 stage or better for SW. I wouldn't get anything slower than 50 gpd because it's painfully slow!! You can find them new for about $175-225. Used you should be able to find for about $100, BUT beware because often on used ones, or ones that haven't been used for a long time, the cartridges need to be replaced, and they are the expensive part! Check out J&L's pricing for units and cartridges.

I have this unit: http://www.jlaquatics.com/phpstore/store_pages/product-info.php?product_ID=ro-afb050 When I bought it, it was $189 last December. Price sure went up a lot. :(

Here's a price list from J&L:

1 micron (1st stage) - $7.45
Carbon block (2nd stage) - $13.95
50 gpd RO membrane [for my unit] (third stage) - $79.95
Mixed resin DI cartridge (fourth stage) - $31.95

Total - $133.30 +taxes

So keep that in mind if you're buying used. ;)

[likwid]

Do you think RO with DI is necessary or would i be fine just getting an RO unit? There are a lot of cheaper ones on eBay that do just RO with 5 stages. Do you think that's enough?

[Myka]

RO cartridges are only so effective:

Filmtec 50 gpd = 98% rejection rate
Filmtec 75 gpd = 98%
Filmtec 100 gpd = 90%
BFS 150 gpd = 98%

So that means if your tap water is 100 tds, then with a 50 gpd unit your product water will still have 2 ppm tds. That's not good enough. The DI resin will take that 2, and turn it into a 0. IMHO, it is imperative to have 0 tds product water which is why you buy a TDS meter as well, and be sure that your unit is working properly.

Find out the rejection rate on the eBay units before you buy. If you're handy, you can buy a 4 stage RO unit on eBay as long as it has three canisters and the RO. Rerun the hoses, and replace the last one with a DI resin cartridge. Just as long as the order the water travels is micron filter, carbon block, RO, DI. Be sure that the flow restrictor rating is the same as your RO cartridge, and that it's placed inline after the RO cartridge. :)