Advice needed. Phos in well water.

pdxmonkeyboy

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So after leaching phos out of acid washed pukani for a year in my 800 gallon setup, it turns out that in the summer phosphates are making it through my eight stage ro/di setup.

What i thought was carbonate exhausting my anion resin may be carbonate and phos. My current setup up is 5 micron<1 micron<carbon<ro membrane> anion resin >cation resin> anion resin>mixed bed resin.

Color changing resins so i know when they are exhausted.

So HOW is phos getting through? Last reading was .25. My 1st anion cartridge is fully spent after 100 gallons but the 2nd one is still fine.

Checked phos on milwaukie mi524? And hanna low range.

Should i add dual gfo catridges? Or more anion?

I recharge anion resin with lye.. i have like 3 gallons of resin.

My sytem evoporates like 10 gallons a day.
 

shwareefer

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I run a 10" cartridge filled with phosguard between my RO and DI cartridges for exactly this reason on well water. I change it once a year but I'm not feeding 800 gallons...
 

Randy Holmes-Farley

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Are you monitoring tds of the effluent? Is it 0 ppm?

Phosphate is one of the harder ions to remove by DI, but i also would not agonize over 0.25 ppm. It's not your main source of phosphate. Foods add much more each day:

https://reefs.com/magazine/aquarium-chemistry-phosphate-and-math-yes-you-need-to-understand-both/

Comparison of Food Sources of Phosphate to Other Sources​

What about other sources of phosphate, like the “crappy” RO/DI water containing 0.05 ppm phosphate? A similar analysis will show it equally unimportant relative to foods.

Let’s assume that the aquarist in question adds 1% of the total tank volume each day with RO/DI to replace evaporation. Simple math shows that the 0.05 ppm in the RO/DI becomes 0.0005 ppm added each day to the phosphate concentration in the aquarium. That dilution step is critical, taking a scary number like 0.05 ppm down to an almost meaningless 0.0005 ppm daily addition. Since that 0.0005 ppm is 40-600 times lower than the amount added each day in foods (Table 4), it does not seem worthy of the angst many aquarists put on such measurements. That said, tap water could have as much as 5 ppm phosphate, and that value could then become a dominating source of phosphate and would be quite problematic. Purifying tap water is important for this and many other reasons.
 
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