Adding DI to RO?

BlueOnTwo · #1 10-21-2009, 05:08 AM

Okay up until now, I thought RO and RO/DI was the same...guess not? I have an RO unit that is built into my house for drinking water.
Would this water be suitable for a saltwater tank? Anything I can do to make it better? I would like to have fish/corals/lps...

Any ideas about adding just the DI unit?

If this is not okay, is there anywhere in Calgary that sells RO/DI water? I need about 80 gallons. If you know where, can you please post location and pricing?

Thanks

hillegom · #2 10-21-2009, 06:59 AM

The water most likely will be suitable with your ro unit. How old are the filters? First buy an inexpensive TDS meter.(total dissolved solids). Then you will know the quality of the water before and after the RO. If the tds is too high upon exiting the RO filters, then you need to add the DI filter after the other filters. This would bring the levels down even more. It all depends on the quality of the water in, To how good the water is comming out. I cannot remember exactly what the % of removal is, but somewhere around 90-95%.
So if the tds into the filters is 100, then comming out is about 10.
A tds meter, will also tell you when to change filters.
For sure if you are going to have corals, then use that ro filter and buy a di filter as well.
I am sure someone in Calgary can tell you what the tap water is like in Calgary

wickedfrags · #3 10-21-2009, 12:30 PM

The "DI" is the final component in the RO system. Not required for a reef tank but recommended for sure. You will not want DI for your drinking water, it makes it real bad. Don't need to spend a lot of money on an expensive unit, I have spend $150 and $850 (back in the day) for an RO unit, they provide the same results. I use a modified 100GPD aquasafe unit to protect my reef.

mike31154 · #4 10-21-2009, 04:36 PM

An add-on DI cartridge should be available for around $40. Depending on the system you have now, it simply needs to be plumbed in somewhere downstream of the RO membrane and after the drinking water supply. As mentioned, DI water is not pleasant or suitable for drinking since it's rather tasteless at 0 TDS.

BlueOnTwo · #5 10-21-2009, 06:12 PM

I dont think installing a DI unit into my drinking water is feasible in my situation. RO makes water 95% pure and RO/DI makes it 99%. Is that 4% going to make a big difference? The cartridge for my RO was changed a couple months ago and is still new.

Should I be concerned about anything? Any other tests I can do other than the TDS? And if I do use just the RO water (which I most likely will), should I add any chemicals to help it?

Of course, I want the best for my tank but I guess I might have to settle for second best.

mike31154 · #6 10-21-2009, 06:27 PM

RO is better than tap water, so probably better to use it than not. DI functioning properly will provide 100% purity, not 99%. Should take the TDS to 0 as I mentioned before. The advantage to this is that you're starting without any unkowns with your system. It's not possible to tell what type of contaminants or solids that 5% TDS remaining in your RO water is. I started my system with tap water and am still dealing with somewhat of an algae problem. No telling how things will turn out for you, perhaps some folks from Calgary can chime in here as to the quality of your city water.

As far as testing for things other than TDS after the RO, that would be difficult without knowing what you're looking for and most hobby test kits would not provide any useful information at the very low levels you'd be looking at. No need to add any other chemicals after the RO either, unless you're dosing your salt mix to correct any levels that it may be deficient in, such as calcium, alkalinity or magnesium. The RO and carbon pre filters on your system should take care of the nasty chlorine which many fresh water hobbyists neutralize using tap water conditioner. You won't need to do that.

hillegom · #7 10-21-2009, 06:31 PM

After you attach the DI, the output is only used for your aquarium. The output is not plumbed into your drinking water.
Which cartridge was changed? the ro membrane? or one of the filters before?
It all depends on the tds of the input water. If it was say 1000, then a DI would be very helpful