Question for AZDesertRat

[NCC-1701]

I live in Houston and we are on a surface water system. My inlet TDS typically runs 165 PPM and my product water typically runs zero. I am using the ½ micron sediment filter and the ½ micron carbon block. I am also using the spetra select 60 GPD membrane.

Knowing that zero TDS is not zero I am wanting to add a DI stage. I am also seeing a small amount of algae growth, so would I be OK to add one stage of DI filtration with the silica buster filter based on my low numbers on the inlet and product water TDS? The spetra pure guys are suggesting a maxicap two stage DI filter, but I do not see the need for the extra expense with my inlet and product TDS so low, but I am open to input.

Thanks for your help

[Randy Holmes-Farley]

The rat will certainly have his own answer, but IMO, if the TDS reads 0 ppm, then the input of nutrients from fish foods is far higher than coming out of the DI resin. :)

[AZDesertRat]

Randy is right on. Its very unusual for an RO only system to register 0 or even close but it appears yours is working very well.
You may still want to consider a SilicasBuster DI though as silicates and phosphates do not register well with hobbyist grade test kits or TDS meters. It may help your algae issue but it like Randy says foods and husbandry could be contributing far more than RO water at those levels.

[NCC-1701]

Thanks for the feedback. I do change out approximately one percent of the water each day and only feed the fish as much as they will eat in a couple of minutes twice per day.
The algae problem is very minor in nature, so I was wanting to find out of it would be worth the extra expense to add a DI stage to my RO system with the low TDS numbers that I am seeing. I know with the surface water supply that we are on there has to be a great deal of runoff present.

[Boomer]

Rat

silicates and phosphates do not register well with hobbyist grade test kits or TDS meters.

I disagree with that strongly, where do you get that from ?

Granted that PO4 and silica have a low R-EC. But it the TDS is zero it is not an issue.

And if what you said was true, them what good would a SilicaBuster do, as there would be know way to test or check them, based on your remarks. So, one is just suppose to accept it as "because I say so" who ever that is ?

Many PO4 kit in this hobby detect PO4 to 0.02 ppm or there abouts. Even expensive lab grade kits or spectro-colorimeters do not go any lower than 0.02 ppm. So, it is any kit or spectro-colorimeter.

There are a couple of hobby kits that test to low levels, Salifert to 0.03 mg/ l, the other SeaChem, to 0.2 mg / l.

Do you have any data that says otherwise ?

IMHO a SilicaBuster is a waste of money, until proven otherwise. And it is a in-bond tank issue and not RO/DI water unless that DI is depleted.

[Billybeau1]

Well, regardless of all of that, I believe adding a di to his system can only help matters. Whether it is a Silicabuster, Silicamax or just a plain di cartridge.

I really doubt he is getting true zero tds out of a system not using a di cartridge. :)

[Boomer]

DI yes, agree, SilicaBuster as an extra DI, no ;) I also doubt it is 0 TDS:D

[Randy Holmes-Farley]

Actually, I misunderstood and thought he had one DI and was considering another.

The spetra pure guys are suggesting a maxicap two stage DI filter, but I do not see the need for the extra expense with my inlet and product TDS so low, but I am open to input.

It may be a money saving choice in the long run. Now that I've been using this new Spectrapure system for a few months, I find I really like it compared to my old Spectrapure system.

If you have one DI, IMO you need to replace it as soon as it rises above 0 ppm TDS. This way, all DI resins get taken out of action at 1 ppm TDS.

If you have two DI's, you can run until the first is quite depleted (say, dropping the post RO TDS by 1/2), and then toss the first one, swap the second to the first position and add the new one into the second position. This way you always have 0 ppm TDS water, but every DI cartridge is used up to say, 3-20 ppm TDS, depending on the post RO TDS.

So you use each cartridge more fully, with the same effluent purity. :)

[Boomer]

Yup Randy I see that . I have a guy now running 3 DI's because in Long Island they boost the Zinc Phosphate once in awhile to 1 ppm and ever time they do he losses inverts. His DI was fairly depleted at each time but he still does not "trust" things. IMHO it is the stirring up of the tank when he does these water changes or the levels are at a level where any addition of metals from the boost that makes it through the RO/DI brings things up toxic level. The tank has been running for + 20 years and has the original bottom sand/gravel layer and rock. We will find out soon enough wwitha all new RO/DI

[NCC-1701]

Randy, Boomer, Billy and AZ:
1) Randy: What type of DI filters are you running?
2) Randy: And would these same filters be correct for my situation?
3) All: Sounds like you are saying that I do not need the maxicap system with my low TDS numbers, is this correct?

[AZDesertRat]

No not saying that at all. If you only want a single cartridge I would opt for the SilicaBuster as it will give you significantly longer life and higher water quality than normal mixed bed resins. If you combine that with the MaxCap cartridge which acts as a roughing cartridge you would be assured of 18 + megaohm resistivity water and tremendous DI life. It will extend the SilicaBuster cartridge by a factor of 3 or more. In my case it was more like 5 times the life and made the SilicaBuster cartridge last over 18 months and was still going strong when I sold the original system after somewhere over 2200 gallons of DI water with a tap water TDS over 800.

[Thefilterguys]

NCC-1701 first of all Silica should be a non-issue for you and your right in your observation a MaxCap and SilicaBuster are overkill. Your Membrane has a rejection rate or 98-99% for silica and a single mix bed DI cartridge will be more then enough to give you ultra pure water for an extremely long time.

People often think their water is the source of issues they see in their tank when infact it is the purest thing they are adding.

Jim

[lancer99]

<a href=showthread.php?s=&postid=12233470#post12233470 target=_blank>Originally posted</a> by Boomer
Rat

silicates and phosphates do not register well with hobbyist grade test kits or TDS meters.

I disagree with that strongly, where do you get that from ?


So do or don't TDS meters read TDS accurately?



<a href=showthread.php?s=&postid=12234322#post12234322 target=_blank>Originally posted</a> by Randy Holmes-Farley

If you have two DI's, you can run until the first is quite depleted (say, dropping the post RO TDS by 1/2), and then toss the first one, swap the second to the first position and add the new one into the second position.... :)

Why not three or four?

This way lies madness!

-R

[Randy Holmes-Farley]

Randy: What type of DI filters are you running?

I buy mine from Spectrapure. I think they are a fine choice for any RO/DI, as long as they fit.

http://www.spectrapure.com/St_replac_p4.htm#MaxCap

Why not three or four?

This way lies madness!

:lol:

Maybe, but I don't think there is a big advantage of 3 or 4 over 2. :D

So do or don't TDS meters read TDS accurately?


Not sure what you mean by that, but a TDS meter (especially in line, IMO) is a perfect way to monitor RO and DI processes, whether they are perfectly calibrated or not. A good one certainly reads TDS accurately.

All: Sounds like you are saying that I do not need the maxicap system with my low TDS numbers, is this correct?

There is equal need to use the DI regardless of the TDS of the effluent. Just because the TDS of the tap water and so the RO water is higher for some folks does not by any mea ns that they have more of the actually undesirable things in the water. TDS is not a measure of bad stuff. It is a measure of all stuff that is ionized, most of which is just simple salts like in your salt mix.

[Thefilterguys]

So do or don't TDS meters read TDS accurately?

TDS meters read perfectly fine for what we are doing and I highly recommend the dual inline as the best option. With a meter such as the COM-100, Which is an excellent meter, you will get a reading just above zero even for ultra pure 18 meg ohm water which leads so people to say zero isn't really zero but were not making semi-conductors here. The problem with handheld meters is they tend to go into the drawer with everything else we were going to faithfully use and don't come out until we see a problem. Inline meters are attached to the system and can be referenced in a moment and are always ready. The readings we want to watch are the RO and DI product water so we know how our system is performing.

Jim