Simple and easy ATOI started hooking up my ATO 2 days ago. Here are some things I noticed.1. No directions. I'm OCD wtih wanting to know exactly how it has to go. The setup in my box was not the configuration of the picture, so I used the pic on the box to figure it out.2. It did not fit on the rim of my sump, but I was able to mount it to the baffle so that was fine.3. I am using an aqua lifter pump to feed it.4. After it got to the level I wanted, the new water being pumped in appears to be dripping from everywhere. However it is just the water being pumped in. I was expecting it to pour out in short bursts.Its only been 2 days, but my level of where I set my float and marked on my sump has maintained perfectly. I normally top off a gallon every other day but have not had to. This will make vacation easier. Its one thing to ask someone to feed your fish. Its another thing to ask them to start adding water to certain levels.Very happy so far.Remarkable. After 55 years in the hobby I do not get excited about many products. This float valve took the functioning of my sump to a whole new level. I can now keep the water level within 1/8 inch, and only have to add water to the reservoir that feeds the sump every 6 weeks. Previously I was dealing with adding water every 3- 4 days, and always fearful that I would forget to fill the sump, and the system would fail. The design and manufacturing in my opinion are of very high quality. It does require some technical know how, and I am a "tinkerer". Be sure you add teflon tape to screw threads under water pressure, and install unobstructed in it's own corner of the spa, and handle gentlely. All of the float mechanism is above water so the chance of a snail or debris interfering is extremely low. Other options float valve options are a lot more expensive, at times require a pump, controllers and electronics to work- all of which are significant sources of failure and flooding of water. Probably the best addition to my aquarium technology base since LED lighting.Lots of level adjustments and small float. Easy adjustments hangs and secures solid to sump. Very well made and engineered. I don’t have a lot of room in my sump so this was nice as it is small. I did not use the drain hose that came with it (very cheap hose) I used ¼” plastic hose from Home depot that comes from my RO filter and I put Teflon tape on the fitting no leaks. This valve is set 2” above my water line as a safety if my electric valve sticks open this will shut off the RO water when sump water raises 2”. I did shut it off when water was on I used my hand, it shut off water great with no leaks. Would work great with a top off tank with “minimum water capacity” or a safety backup for a RO system, would not trust anything without a backup as everything mechanical will fail sooner or later. This valve shuts off the water mechanically almost the same as an old float fill valves in a bathroom stool and has NO electrical, electrical shut off or switch.First let me say, I like the thing. I use it as an auto-top-off solution, and it's literally one of the only float valves correctly sized for a sump tank. . I'm glad I bought it and saved $$ over an expensive ATO like the Osmolator. However, a couple of drawbacks:Construction isn't the best. It's a bit "wobbly" when mounted. The insert where the hose goes in is less-than-reliable. The hose doesn't fit in watertight very well, it takes a lot of maneuvering to get the drips to stop. I've also had it pop out, and nearly flood my sump before I caught it. There's also no way to turn it off for water changes, etc.Out of the box, I wouldn't necessarily see this as "set it and forget it." I ended up permanently sealing the inlet with glue and silicone, and put a ball valve on the hose a few inches from the intake. That way not only is there a nice tight seal on the inlet, but I can stop the flow during a water change etc.I'd recommend it to people, but only if they realize that you have to take some steps to ensure it's reliable functionality.This was a very easy Auto top off valve to install in the sump of my saltwater reef tank. This is very well built, and works perfectly. Other reviews give it very low stars for breaking while installing. Just remember it is made of plastic and acrylic so there will be no rusting parts at all. Just don't over tighten anything, cause if you do, more than likely, you will snap something. The water line comes in from the top which is very intelligent cause it is mounted to the side of your sump, so the line doesn't have any kink or awkward bend on it for unrestricted flow. I have had this product up and running for a few months now and it has no flaws in my opinion. Works like a charm. Hope this helps you out on buying an Auto Top Off that actually works how they are designed to work.I have it mounted in my tank as an auto top off. It is not the best option for that because of the way it mounts. You see a lot of hardware inside the tank. You also have to get your hands in the water to screw it into place. It works, it is just not awesome and the float its self is not adjustable. You can rise it up and down on the mounting bracket, but the angle of the valve is fixed to sit straight out. I will buy a different one the next time I need one.Keeps the water level up