RO or RO/DI ?
 

I bought a 4 stage RO filter for my aquarium water and drinking water.

Does the deionizor make a difference for aquarium top-up water or is RO enough?

Do you have a tds meter? With RO/DI you should be around 0-4ppm, I'm not sure what it would be for just RO.

The place where I bought my RO unit from had a spigot with a little light and built-in TDS meter. It's supposed to turn on to let you know when your TDS rate gets above a certain level and then you know it's time to replace consumables.
The guy helping me out told me that in Victoria this is a waste of time because regular Victoria tap water tests at 0 on a TDS meter.

I'd go somewhere else to purchase the unit then as obviously the guy knows squat about what he is selling.. :lol:

I think he must have been referring to that particular TDS meter built into the spigot. Probably garbage without a very sensitive scale or something.

I would get a tds meter from www.jlaquatics.com

Install it, check your ppm for RO, then for RODI, and decide from there.

If you have an RODI, then I would use it for the reef, but for drinking water you need to use just RO water.

Your 4 stage didn't come with a DI canister? You can buy add-on ones for pretty cheap, I would do it.

I think it is very important to have DI as well. It is very good for removing silicates and polishing the water after the RO stage is complete.

If you remove the DI component from the system and plug in a TDS to just the RO section you will get a pretty high PPM reading still. Attach the DI and watch it drop to nearly 0.

At home I have 2 TDS meters in my RO/DI so I can measure the water at each stage. Water comes in from 200 - 300ppm, is about 30 - 40 ppm after the RO stage and 0-6 ppm after the DI. (This is just from memory)

I am getting a MAKO system soon with 2 DI Units instead of the 1. I am expecting 0 ppm permanently from this.

I can give you actual readouts if needed.

Keith

That's wrong. I usually read around 14-17 ppm on my tap water....

My 4-stage has 4 canisters; a mecahnical pre-filter, two identical carbon cartridges and the RO membrane canister horizontally on top.

I think I will add on the DI to this.

Thanks for the good intel.

You probably don't need the duplicate carbon, but I guess it can't hurt.

I'm thinking of buying a second RO system for lake water at our cabin and there's one for sale used locally.

Is the diffence in most of these systems in the filters and cartridges? They look like they all are about the same size, so buying a used system and replacing the consumables with high grade sounds like maybe a good way to go?

Or are there different *standards* for these things as well?

10" canisters are standard. The RO membranes are also pretty standard, so everything is usually replacable, but for the used one you are looking at you should verify that they are 10" canisters, then you can buy replacements.

The only real differences between units are build quality, and some features like built in TDS, build in hydraulic switch, pressure gauge, and the total GPD the unit can pump out.