Using DI water only in the LMD.... why not?

[Chin_Lee]

I was at a LFS a couple of months ago and I learned that he does not use RO - he only uses DI to make the top off replacement water. I have been thinking about it since and with the summer months coming, I recently decided to collect the waste water from my RO unit to use it to water my garden.

I make 50g of RO water each instance and i collected approximately 100g of waste water. My input TDS reading is 8 and after RO/DI, my TDS reading is 0. To make 50g of RO/DI water, I had to use 150g of water. If I made DI water only, 50g of water would yield 50g of DI water.

Today I started reading this thread on RC on how to recharge DI resin.
http://www.reefcentral.com/forums/showthread.php?threadid=1144161
Although the chemicals are caustic, its commonly sold at hardware stores and are no less caustic as some of the chemicals that we use on our toilets, bathtubs or clothes.

So my topic/question for discussion is primarily targeted at (but not limited to) those who already have an initial low TDS reading: why don't we all just use DI water instead of the RO and DI?

[fkshiu]

There is no reason not to use DI-only water in the GVRD. I used to use DI only water when I had a 46 gallon in the form of an AP Tapwater Filter. The only reason why I went RO/DI is because the AP just couldn't produce enough DI water conveniently for a 150g system.

I believe OA uses DI-only water the last time I checked there.

A full-out RO/DI system is an added measure of filtration when the water quality does go down such as what happened around here last winter - although the pre-filters took the brunt of the extra turbidity rather than the RO membrane.

[ClubReef]

DI is for final water polishing via Ion exchange..it's like squeezing the last drop out of a sponge. The bulk of the filtering process is done through the RO membrane. Here are some stats from Spectra Pure website www.spectrapure.com:

RO unit:
remove over 98% of all ionic impurities
remove over 95% of organic impurities
remove colloidal and particulate impurities
remove microorganisms and pyrogens
remove chlorine, chloramines, pesticides etc.

RODI unit:
remove over 99.9% of all ionic impurities
remove over 95% of organic impurities
remove colloidal and particulate impurities
remove microorganisms and pyrogens
remove chlorine, chloramines, pesticides etc.

In my opinion, why bother with the DI filtering if you're going to skip out on the reverse osmosis step that takes out 98% of the ionic impurites? DI is a marketing gimick IMO..it's to sell the dang unit..in most applications it's not needed.

[Zylumn]

You are very lucky to have a tds reading of 8 out of your tap. Yesterday 184 out of mine. At 8 my fish and water bottle would get it right out of the tap.

[ClubReef]

This time of year in Calgary is extremely bad due to mountain run offs.....I bet if we did a study on Non RO reefers in Calgary, most will experience some sort of algae bloom this time of year??? Our water is sad :(

[Zylumn]

I tested from 2 pails of water left out in this last rain we had. one pail was 4 and one was 7. ????

[Chin_Lee]

DI is for final water polishing via Ion exchange..it's like squeezing the last drop out of a sponge. The bulk of the filtering process is done through the RO membrane. Here are some stats from Spectra Pure website www.spectrapure.com: (http://www.spectrapure.com:)

RO unit:
remove over 98% of all ionic impurities
remove over 95% of organic impurities
remove colloidal and particulate impurities
remove microorganisms and pyrogens
remove chlorine, chloramines, pesticides etc.

RODI unit:
remove over 99.9% of all ionic impurities
remove over 95% of organic impurities
remove colloidal and particulate impurities
remove microorganisms and pyrogens
remove chlorine, chloramines, pesticides etc.

In my opinion, why bother with the DI filtering if you're going to skip out on the reverse osmosis step that takes out 98% of the ionic impurites? DI is a marketing gimick IMO..it's to sell the dang unit..in most applications it's not needed.

but how do you explain 0 TDS reading on the output on DI only filtered water?

[ClubReef]

You get 0 tds reading on a DI only cartridge? I can see 8% TDS down to 6% or so..but complete 0? I can't explain :(...but if it's that simple and you trust your TDS meter than it's obviously eliminating dissolved solids.. Mechanically I can't see how it can be complete 0 though??

From an 8% to a 0% drop means that all of the content in the original water is in the form of Ionic impurities. This implies that there were no Organic impurities, particalte impurties, microorgasms, chlorine, pesticides etc in your original water because DI does not eliminate these..only ionic components through ion exchange...see where I'm going here ??

[skylord]

I was asked to try this a couple of months ago and found my TDS meter also reads 0% with DI only. Ive been using DI water since and I'm not noticing any adverse effects. With my current system it works well for me. When we get into our new home and the larger system is running I think I will go back to RO/DI but my system will be more automated.

Scott

[Quagmire]

I think the biggest reason we use RO is to lengthen the life of the DI resin.If you only use DI,the resin will have to be of a very high quality (not mixed bed)or you will be recharging between every use.Ive been looking into this for quite a while now and it seems Kati/ani from Germany is the way to go.Seems expensive at first,but the life of the resin and the ability to recharge numerous time would make it worth looking at.Also if you are having a problem finding lye for recharges,check out the soap stores.Lye is used to make soap,and these places usually sell it for making home made soap.

[Jason McK]

I'd be very curious to find out what stage of our 5 stage units is removing most DS. simpley removing the RO membrane may not be the best proof that the DI is the filter since we all have a carbon filter and a pre filter. Could it be possible that in GVRD a prefilter carbon filter and DI is all that is required?

J

[Chin_Lee]

I'd be very curious to find out what stage of our 5 stage units is removing most DS. simpley removing the RO membrane may not be the best proof that the DI is the filter since we all have a carbon filter and a pre filter. Could it be possible that in GVRD a prefilter carbon filter and DI is all that is required?

J
i think thats probably the key there Jason. On my RO filter, I added two prefilter stages with 30 and 10 micron cartridges on top of the three on the original RO system.
I think if we were to bypass the RO filter and straight to the DI filter at a slower rate, it would work. I'll test it out later this week.

[christyf5]

I seem to be able to grow algae using RODI water with a TDS of zero. Quite frankly I'm scared to only go with DI water, although I've contemplated it several times.

[zulu_principle]

Chin sent me a PM so I thought I would just post my reply here.

I have been only using DI for about 5 years now. That being said I am metered for my water consumption, and my recollection is that it is somewhere near 4 times that of the residential rate.

My system runs a 5 micron prefilter, then 10 micron carbon then triple DI, we aim for TDS of 4 or below and then start changing the filters.

We have had issues but I cant claim they were from using DI only resin.

As for using the chemicals to recharge, not sure with the toxic nature of the chemicals, the water savings, and a value for our time that it is more "economical" to just use a few more DI Cartridges.




Wendell

[SusanB]

What kind of system uses 150 gallons to yield 50 gallons? Our reject at work was only about 10% (but that's for Vancouver water). Still, a reject of 66% is way out of wack. People initially went to RO because it was cheaper and the membranes lasted longer, but it does depend on your feed water, prefiltration etc, as well as what you're trying to remove from your water.

[skylord]

Im using the Kent Marine Maxxima Hi-S RO/DI Filter - 60 GPD and my rejection is very close to what Chin's is. While Im not on a metered water system I dont have a garden for the reject water and it seems like such a waste to put that much down the drain. When our new house is completed (Aug) I will most likely use Chins suggestion and use the reject water in the yard/garden.

Scott

[fkshiu]

Chin sent me a PM so I thought I would just post my reply here.

I have been only using DI for about 5 years now. That being said I am metered for my water consumption, and my recollection is that it is somewhere near 4 times that of the residential rate.

My system runs a 5 micron prefilter, then 10 micron carbon then triple DI, we aim for TDS of 4 or below and then start changing the filters.

We have had issues but I cant claim they were from using DI only resin.

As for using the chemicals to recharge, not sure with the toxic nature of the chemicals, the water savings, and a value for our time that it is more "economical" to just use a few more DI Cartridges.




Wendell

And there you have it. If a commercial operation can do it, there's no reason why a home system can't.

Of course, it was only the neat little drinking water faucet that came with my Aquasafe system that sold the wife, so I would've still ended up RO/DI in any event =)

[Chin_Lee]

What kind of system uses 150 gallons to yield 50 gallons? Our reject at work was only about 10% (but that's for Vancouver water). Still, a reject of 66% is way out of wack. People initially went to RO because it was cheaper and the membranes lasted longer, but it does depend on your feed water, prefiltration etc, as well as what you're trying to remove from your water.
SusanB
what system do you use at work that used 10% waste? if I can reduce mine to 10%, i will continue to use RO/DI. But I know my waste water ratio is not out of the norm.

[Chin_Lee]

Chin sent me a PM so I thought I would just post my reply here.

I have been only using DI for about 5 years now. That being said I am metered for my water consumption, and my recollection is that it is somewhere near 4 times that of the residential rate.

My system runs a 5 micron prefilter, then 10 micron carbon then triple DI, we aim for TDS of 4 or below and then start changing the filters.

We have had issues but I cant claim they were from using DI only resin.

As for using the chemicals to recharge, not sure with the toxic nature of the chemicals, the water savings, and a value for our time that it is more "economical" to just use a few more DI Cartridges.
Wendell

Wendell
why not use the 10 micron carbon and then the 5 micron prefilter? Did you find that config would clog up your carbon filter too quickly?

What type of DI filter do you use? Is it the Aquasafe refill your own resin container?

As far as the toxic nature of the chemicals, i believe there is a final process to counteract the chemicals.

As far as economical sense, would it not be easier to collect all your used DI resin for a few changes in a container and then recharge them all at the same time using the procedure?

[Veng68]

Hey Chin,

If your seriously going to recharge DI resins......... for a bulk supply of pure lye....... try Cranberrylane make it yourself body care store in Coquitlam

http://cranberrylane.stores.yahoo.net/soapmaking-supplies-solids-sodium-hydroxide--.html

Cheers,
Vic[veng68]

[zulu_principle]

Wendell
why not use the 10 micron carbon and then the 5 micron prefilter? Did you find that config would clog up your carbon filter too quickly?

What type of DI filter do you use? Is it the Aquasafe refill your own resin container?

As far as the toxic nature of the chemicals, i believe there is a final process to counteract the chemicals.

As far as economical sense, would it not be easier to collect all your used DI resin for a few changes in a container and then recharge them all at the same time using the procedure?

Hi Chin

I have always used the cheapest filter first, not sure what would happen with the carbon first.

I use the "nuculear grade" color changing DI filters.

I understand the conversion of the chemicals but having stuff like that around could result in someone using something for the wrong purpose, etc.

Probably true but its a matter of priorities.

All the best.


Wendell