Actually I think this is a great thread even if there is a few disagreements nothing is out of hand and I can see where people are getting frustrated as alot of things can be missed when writing down things and not actually being able to communicate face to face. I have also read somewhere that rays get there water from the food they eat, I'll try and find a link later. When I started this thread I didn't realize where it would go or what other questions it may bring up. The one thing I'm wondering and am lacking experience in is that what is going to be the differences when dripping through different filters. I know most drip system contain a 1st stage sediment filter then a 2nd stage carbon filter, now some people use a 3rd stage carbon filter or hma (never used a hma so not sure if this is the correct stages for them). So with both of these systems our ph will stay the same but we will be removing different minerals. Even with these systems are we removing the minerals that rays need to be healthy? I know with my sediment/carbon/carbon my tds drops from like 500 to 490 so not much of a difference but I still am having no problems with keeping sensitive rays. So maybe high tds is not so much as a concern as certain minerals in the water. I have three different systems 2 with drip systems on them so I will try my regular sediment/carbon/carbon on one a sediment/carbon/hma on another and just straight on another and get some readings. All I have is a tds meter and a Hagen master test kit so can't get alot of readings, I'll also grab maybe a conductivity meter if they work better than tds. I could also fire up my merlin r/o unit and get some numbers.