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					Originally Posted by  gregzz4
					 
				 
				A testing problem I have is the Elos turbidity kit has a small range between 300 and 400, so it's near impossible to tell what the results are 
			
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 I have this kit.  It's pretty easy to use.  I always use it under the same bright white fluorescent lamp so I have good, consistent lighting.  It's quite easy to tell the difference between 300 and 400 ppm.  I'm confident I can use the kit with +/- 15 ppm.
FWIW, my maintenance is about the same as all you guys.  I test SG, Ca, alk, Mg, K once a month-ish, and it takes maybe 15 minutes because I have them all going at the same time.  

  NO3 and PO4 
maybe quarterly just for interests' sake.