Posted: Fri Mar 22, 2013 12:54 am Re: What type of R/O system do you have?
You don't want to use straight RO water in a freshwater tank. It's too soft to hold a stable PH and it can even cause pitting in your turtle's shell. You definitely want to mix it with tap water or even better buffer it with something like Kent's RO Right or Brightwell's Remineraliz before adding it to your turtle tank.
All RO units operate the same. No one brand is better than another except for perhaps customer support or price. All RO units will produce near 0 TDS water. (for 0 TDS pristine water, you need a RO/DI system)
RO systems marketed towards the aquarium hobby like Spectrapure are $$$$. A step down in price are units from the hardware store that carry appliance name brands like whirlpool. The hardware store units aren't very customizable. You can't easily add on a stage or change things should you want to. I actually prefer the generic RO systems. I got mine at purewaterclub.com The most basic units start at $60 on their site. I got a 5 stage RO/Di for like $110 shipped. All of the replacement membranes, pre filters and parts are available there for cheap. The nice thing about a generic system is that you can get parts / replacement stuff for it most anywhere. Each of the stages are connected with tubing and quick connect style fittings available at any hardware store. If you want to put a T in the line after the pre-filters with a shut off valve... you could. If you want to add in a DI stage later, you could. If you wanted to add in an inline TDS gauge to let you know when the membrane was needing to be replaced, you could. You could change out parts like the flow restrictor, the check valve, and the auto shutoff valve easily as these sometimes fail. It's also easy to swap out a membrane and flow restrictor to convert a 60GPD unit into a higher GPD unit if you wanted to.
The higher the GPD rating of the membrane, the less efficient the unit is. The higher the GPD of clean water a membrane is capable of, the higher the ratio of waste water. A 60GPD unit will use less total water to make say 600 gallons of RO than my 150GPD unit will. My 150 GPD system will do it faster but produce more waste water in the process. Remember also the flow restrictor needs to match the RO membrane rating.
For storage you probably don't want a pressurized container with a bladder. Those are best for storing 3-5 gallons of drinking water. For storage, you'd be best off with a plastic container like a small-ish round garbage can. You can use a float valve to stop the water when the bin is full. The float valve will block the clean water output line and trip the auto shut off valve on the RO system. You can then use a small utility pump like a $15 maxijet to pump the RO water into your turtle tank should you want. The garbage can would give you easy access to the stored water so you can mix in the buffer. The same $15 utility pump can be used to stir the buffer into the water.
