Checking RODI water for P04
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Screwgunner
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No test kit for rodi water you need a TDS meter (Total Dissolved Solids ) you want it 0 if it is above 4 or 5 your filters need changed.
Screwgunner
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No problem. If your rodi water reads any tds it will probably be chlorine. If you live in the city carbon blocks will be your best friend . Chlorine will ruin a RO filter pretty quickly. If you are on a well it should last you a very long time.
Randy Holmes-Farley
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I'd use the Hanna ULR phosphate checker, but do not be concerned with seeing some. I address that here:
reefs.com
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.
Aquarium Chemistry: Phosphate And Math: Yes You Need To Understand Both
Foods are by far the most important source of phosphate in most aquariums. In considering whether sources of phosphate other than foods are important, one must carefully look to the actual amounts involved to determine whether other sources are even worth trying to minimize.
reefs.com
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.
While a TDS test is good for testing RO/DI water, don't assume readings above 0 are only chlorine. I use the Hanna tester Randy referenced for both salt water and RO/DI water (when the TDS looks out of the ordinary). Some phosphate remained in my RO/DI water. At Randy's suggestion, I added a second DI unit to help reduce it further.
Randy Holmes-Farley
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I agree that TDS readings on RO/DI effluent are almost certainly not "chlorine" as Cl2. It wouldn't be conductive and hence not detected. .
Randy Holmes-Farley
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I don't think that says much and isn't a problem.
