RO/DI and phosphates

[mjrwingnut]

I live in a rural area and treate the well water with a ro/di. I still have high level of phosphates. Any Idea on how to lower the phosephates? I currently use phosguard pellets to absorb the phosphates.

Shouldn't the ro/di absorb the phosphates?

 

[DrDNA]

if you are on well water, make sure you are not using up your DI resins in a very short amount of time. I am using well water in loomis and it is high in dissolved CO2 and my DI cartridges only last about 10% of their rated life (fortunately, I can recharge them rather than throwing them out). You may want to test the carbonate hardness and pH of your well water, and there are online calculators where you can calculate your dissolved CO2 in your source water.
Also, are you running any TDS meters on your system? make sure they are still reading "0" on your product.

 

[MandM]

How do you recharge DI resin? I see mine staring to change color within a few days. My tap water is gross.

 

[mjrwingnut]

I tested the TDS and it's zero. I haven't tested the ph or the hardness, but I will tomorrow.

How do I recharge my DI resin?

 

[Brian Prestwood]

Hey Sheila

Recharging DI resin is not a trivial task. Larry Robison and I did it once. For mixed bed resin, you have to seperate the cation pellets from the anion pellets.

You soak the mixed bed resin in a strong base, e.g. kalkwasser. This seperates (floats) one of the two. You then have to decant the floating resin off and treat one of them, don't remember which, with a strong acid, e.g. muratic.

IME - mixed bed resins work best when they are actually mixed, not just layered. So, you have to mix it together again for best results.

 

[DrDNA]

recharging DI resin is a PIA if it is a mixed bed, like Brian said above. I don't recharge the mixed bed stuff, I just buy the mixed resins in bulk.
One thing that spectrapure recommended for dealing with high CO2 levels is to run a straight "stong base anion", or SBA, cartridge ahead of your standard mixed bed catridge. since the SBA catridge is anion-only, it is relatively easy to recharge using a strong solution of sodium hydroxide. I dump the contents of the catridge into a container, add a little DI water to it and slowly add the sodium hydroxide pellets and stir until the di resin starts to float. then rinse several times with di water, put it back in the catridge and into your RODI system, and follow the rinse-up procedure for new catridges.

 

[Brian Prestwood]

Jeff

I'm assuming your DI resins (an/cat) are kept seperate. It seemed to me that it worked better when it was mixed, not layered or two cartridges. Have you noticed that?

 

[DrDNA]

I kind of rearranged my RODI setup as per a recommendation from Spectrapure to deal specifically with high CO2. It goes as follows:

water in --> sediment filter --> carbon block --> RO membrane --> SBA cartridge (this is the one I recharge!!) --> silicabuster or mixed bed catridge (I just throw out this resin mixture and refill it when its exhausted) --> third add on cartridge with seachem's cuprisorb --> collection container

the end result is that I do get zero TDS water, and the trick is to not let the unit run once the SBA resin is exhausted (i.e. turned completely from blue to yellow) or else your downstream mixed bed catridge gets used up in a hurry.

I did experiment with recharging some mixed bed resin using sodium hydroxide and muriatic acid, but it just wasn't worth the effort when you can buy mixed bed resin in bulk and refill the catridges yourself.

I dunno, seems to work for me though.