Switching from RODI to DI only?

[Thales]

Hey guys,

My tap water TDS is 35, so I was thinking instead of wasting all that water making RO that I would switch to a 4 stage DI system (micron, carbon, carbon, DI). My pressure in the current system isn't really high enough, and tops out at like 40 psi. All that combined makes me think my plan is pretty good, but I hear different things. Anyone have any opinions?

 

[capescuba]

This is actually something I have considered also - I think we have pretty good tap water around here so you might be onto something good!

I know I have used just DI water in the past and I can't recall it having any bad effects ..

 

[Ibn]

Man, that's some great tapwater you guys have.

I think that's what Norm mentioned that he used for awhile. He uses a DI filter, but I think he stopped using that and just uses straight tapwater nowadays (w/Prime).

Hopefully he'll chime in.

 

[tuberider]

I think it's a good idea as well, sediment and carbon cartridges, and for that matter DI resin are all pretty darn cheap. Plus I would think you could fire up a batch of water a little quicker. I'll be installing a similar system tomorrow for an auto top-off.

 

[Raddogz]

That's pretty good tap. For some reason SF's tds is all over the place. The tds readings are sometimes as low as 30 as then it can go up to 120 a few weeks down the road.

 

[CitS]

I thought one of the purposes of the RO section was to filter out
larger particles that clog the DI unit too quickly?

 

[Raddogz]

My guess would be if the sediment and carbon block filters take out most the junk the di will not have to work nearly as hard. You need to check the ratings of the sediment and carbon block filters to be sure though as they do come in different ratings.

 

[sfsuphysics]

Yeah if your tap water is really that low, by all means go DI only, and if you don't mind having hazardous chemicals around with the little one you could recharge it periodically as well..

Hell if it were me I might just run sediment + carbon and live with 35TDS in the aquarium water

 

[CitS]

[quote author=sfsuphysics link=topic=2191.msg21717#msg21717 date=1183413109]
Yeah if your tap water is really that low, by all means go DI only, and if you don't mind having hazardous chemicals around with the little one you could recharge it periodically as well..

Hell if it were me I might just run sediment + carbon and live with 35TDS in the aquarium water

[/quote]


Hmm....
Wouldn't that take the salt out?

;D

 

[fishnfst]

Wow.. I wish my tap had a tds of 35.. I thought I was doing pretty good at 175..

 

[nukeproof]

I started using just tap water w/ Prime about 8 months ago when Jim (Bookfish) told me it's not really needed in Alameda. I get more diatom but my corals look the same as when I used RODI. I used the money I save on water to do more frequent water changes. I'll stick with it until our water parameter changes. Pretty happy so far.

 

[Mr. Ugly]

I was doing DI only, and recharging my resins with sodium hydroxide and hydrochloric acid.

I went to tap water and prime about 8 months ago as well. Mainly because the resins were due for a recharge, and the spouse was bitching about the Brute container next to the kitchen counter.

I'll go back to DI at some point, but not in a rush for now.

 

[Mr. Ugly]

[quote author=CitS link=topic=2191.msg21696#msg21696 date=1183393657]
I thought one of the purposes of the RO section was to filter out
larger particles that clog the DI unit too quickly?
[/quote]

The DI doesn't clog, but if your tap water has high TDS, the RO keeps your resin from being used up too quickly. The idea being that most people don't want to keep buying new resin, nor are they interested in playing amateur chemist.

 

[capescuba]

For anyone interested, here is the latest water quality report for http://www.ebmud.com/water_&_environment/water_quality/annual_report/EBMUD_2006_AWQR_3.pdf. Maybe someone here can even make some sense of it

 

[Raddogz]

I know the San Francisco Water Department's annual water report is out as I just got it in the mail.

 

[Ibn]

Take the period out at the end of the link there.

http://www.ebmud.com/water_&_environment/water_quality/annual_report/EBMUD_2006_AWQR_3.pdf

Not really too hard to read. Just find out which treatment plant you're on and then match the colors. This is probably the most useful part of the report, although the ranges are pretty substantial.

 

[Elite]

You guys are so lucky. Water in SJ is over 400. If I don't use RO, the DI resin die after it fill up my 50G container. >

 

[Raddogz]

Oh...I guess I shouldn't complaing about the 135 to 150 range then.

Hmmm...I'm wondering if I should try this out on my lps/softie tank.

 

[Thales]

Hey Guys,

I just got off the phone with Jim from www.thefilterguys.biz - he knows his stuff and actually does aquarium related testing on RODI because no one else does.

He says for the carbon blocks to remove chloramine you need a longer contact time. He suggests 5-6 gallons an hour. Sadly there is no way to monitor such a slow flow, you just have to do it with a bucket.

A DI cartridge will remove about 5100 ppm of TDS before it needs changing. Once you see the color change start, change the resin. Even better, run two DI's just in case. One the resin changes, it can release ammonia, so really, change it.

I am prolly going to go with a 5 stage DI system, micron, carbon, carbon, DI, DI. The carbon busts the chlormine so the DI has a better time of dealing with it. At the same time I am considering just tap water and prime. But, nah, that will mess up my auto top off systems and I like the DI in case something burps in the water supply and its pretty cheap considering the expensive of the system already.

 

[Mr. Ugly]

[quote author=Thales link=topic=2191.msg21763#msg21763 date=1183485567]He says for the carbon blocks to remove chloramine you need a longer contact time. He suggests 5-6 gallons an hour. Sadly there is no way to monitor such a slow flow, you just have to do it with a bucket. [/quote]

I was doing about 7 gallons per hour through my carbon/DI setup which was already on the safe side. 5-6 should be no problem with chloramine getting through.

You can put a needle valve on the tap water supply and adjust the flow for 5gph. Then have the whole thing turn on/off with a solenoid valve or whatever.