Review on Premium Universal Replacement for 4 Stage Reverse Osmosis Systems by Michael Zambrano

I used this filter set to replace filters in a Formula Model III/VIII system. I had no information on this system apart from the brochure I left behind, but it turned out to be fairly standard and probably hasn't been serviced in years. This is by no means an exhaustive list of instructions (they're easy to find on the internet), but here are some of the features I've come across when exchanging. 1) Changed pre-filter. Had to be unscrewed with a strap wrench, otherwise without incident. I cleaned the canisters with a mild bleach solution and rinsed them with about a gallon of water after reassembly to keep the carbon dust out of the new reverse osmosis filter. I also applied a small amount of food grade o-ring lube to the seals. If you don't have these, you can order a handset. 2) Reverse osmosis filter replacement. Again a strap wrench was required, but once loosened it unscrewed easily. If necessary, the old filter can be pulled out with a pair of pliers with a little effort. I cleaned it, smeared the seals with grease, put in a new filter and screwed the cap back on. 3) First problem - my existing post filter had smaller fittings. Bought two adapters at a local hardware store and finished the install. 4) Decided it was pretty easy. They turned on the water and she made a horrible roar, a constant buzzing and knocking. Also, a lot of water went down the drain. After searching the internet I decided to see if it would stabilize in an hour or so - no. 5) A shut-off valve was suspected, which shuts off the water supply when the pressure in the tank is high enough. Unfortunately, I could not find an identical valve that would mount directly to the pre-filter housing. I used one with 4 ports for the Purenex ASOV auto shut off valve, 1 pack - 2 for the RO water supply (the part that shuts off) and 2 for the RO outlet/tank which is the pressure control valve. After a small reinstall it worked but there was still some banging and a lot of water running down the drain making a lot of noise. 6) After more searching and some experimentation I decided that a flow restrictor is also needed on the reverse osmosis drain side. Filter. Popped in a TmallTech 50GPD 300CC 1/4" Quick Connect RO Reverse Osmosis Flow Restrictor (2-pack) and it seems to have worked. Now everything works properly: you pull out the filtered water and the shut-off valve opens. Yes, a trickle of water down the drain for a few minutes while the reverse osmosis filter does its thing and then when the tank is full again it all stops.Sorry I don't have a meter to confirm the quality of the water but it has a great look/smell/taste and also makes a nice translucent ice cream. Happy with these filters and will order again. Hope this gives you an idea of what an older system could need and be helpful.