Hey guys, I completed my AWCS this weekend! I figured I'd show you the setup in detail to make it easier for anyone else who wants to give it a go. I couldn't find anything like this, even though I knew it had been done before, so I had to research different forums, talk to a couple vendors, and pm people before I had everything I needed and knew what to do with it. DISCLAIMER: Neither I or Living Reefs is responsible for any damage to your tank or your personal property or yourself or family members. We're working with electricity and water and if you are like most of us, lots of money on livestock. Please note that I have just set up this system myself and do not yet have any long term data on how it will effect my tank or yours, so if you want to jump in early, you are on your own! Ok, here we go! :bounce: I'm going to show you how I chose to set things up. Some equipment can be modified to suit your particular needs, but this will give you the general idea. I combined my Automatic Top Off (ATO) system with this as well so I will include that, too. Water Storage Gotta have some place to store both your fresh RO water and your fresh Saltwater. You don't NEED to have a RO/DI unit, but trust me... it's a heck of a lot easier, especially for this application, to have your own unit vs carting gallons and gallons of water from the LFS. So what I did was pick up a couple of Food Grade liquid storage tanks from Tank Depot There is a tankdepot location here in Houston do I didn't have to pay shipping charges. You may have something similar near you as well. Do a google search or check with your local saltwater club. There's bound to be a source for water storage somewhere. Some people use Brute trash cans from Home Depot which could be made to work for this too. Get creative. Scroll down a little bit and you'll see what my tanks look like, all plumbed and filled with water. On the left is the freshwater (FW) tank which is 65 gallons. On the right is the saltwater (SW) tank which is 55 gallons. There is a standard bulkhead in the base of the FW tank and then a ball valve before reaching the pump. This FW tank is serving two purposes. One, it's serving as the FW source for my ATO system and two, it serves as the source of FW for when I'm ready to mix up a batch of SW. So if you look at the photo, there is a blue water line that comes down from the top right of the pic, and into the top right of the FW tank. This is the water line from my RO/DI unit which is mounted on the other side of the garage. I drilled a hole in the side of the tank and fit in a mechanical float valve available from any place that sells RO/DI equipment. I get my stuff from The Filter Guys. It looks like this. When the tank is full, the float switch shuts off the RO/DI unit because the RO/DI has an auto shut off valve which shuts it down when it senses back pressure. Once the tank is full, I'll shut the RO/DI off until it drops several gallons before running it again. Right in between the two tanks you will see a pump. This pump is an Eheim 1260. You don't need this big of a pump but I had one already so I put it to use. The pump is used to pump water from the FW tank into the SW tank. So when I'm ready to make SW, I open the ball valve to let water start flowing from the FW tank into the pump. Then I turn on the pump and it pumps water up to the top of the SW tank, through another standard bulkhead and into the tank. I figure I can pump close to 50g into the tank, and this will still leave 15 gallons in the FW tank for my ATO, until the RO/DI is able to fill it up again. Once the FW is in the SW tank, I can now start dumping in salt until it's at the correct specific gravity. Inside the SW is a 400gph pump that will mix the SW and keep it churning. Inside the FW tank is an old Koralia powerhead that will keep things moving. The tanks are up off the ground for a couple reason. For one, i wanted easier access to the base of them for draining purposes. That's what the valve is for at the base of the SW tank... just an emergency drain, or an easy way to fill a bucket with SW. The other reason is that my ATO is working by gravity and I just wanted to make sure that there was enough head pressure to keep the siphon going to my tank. Now I was looking for a quick and easy way to get the tanks up off the ground so I just picked up two water heater stands. They are rated for enough weight for this purpose, but they are expensive and they are galvanized steel... not the best material to use around SW because it will rust. But they will do the job for now. I would suggest if you have the time and tools, to build a platform out of wood. LiterMeter III, Remote Pump and lots of Tubing Ok, so you've got your water storage stuff figured out. Now how the heck do you move water back and forth? You turn to a cool little company called SpectraPure. SpectraPure makes some precision dosing pumps, among other things (like RO/DI units!). The LiterMeter III (LM3) is both a dosing pump and the main controller for additional pumps. We need one pump to push new SW into the tank, and we need a second pump to pull old skanky water out of the tank. So here is what you will be looking for. LiterMeter III Remote Pump Module 1/4" John Guest Tubing I've found that The Filter Guys have the best price on tubing and several colors to choose from. The tubing is FDA and works with the John Guest speed fittings on the LM3 and the RO/DI units. I color coded my tubing. Blue takes FW to the ATO in my stand. White takes new SW to my sump. Black pulls old SW out of the sump. Here's my LM3 and RPM set up next to my storage tanks. Speaking of my sump... you now have to run your tubing to your tank. The room my tank is in is on the other side of the wall behind the storage tanks. So i punched a hole through the base of the wall and came out on the other side behind my baseboard molding. I ran all the tubing along the base of the wall and will cover it with the baseboard. Here you can see the blue ATO supply going to the Eshopps ATO in my sump. Now on the other end, you need somewhere for the old water that's being pulled out of the tank to drain. Do you have a drain in your garage floor or wherever your storage tanks are? I did not. So I ran mine along the garage wall towards the garage door. It just so happened that my sprinkler system's control panel is mounted there. All the wiring for it runs down the wall and outside through some pvc. Well there was JUST enough room in there for me to fit the 1/4" John Guest tubing. After at least an hour of pushing and pulling and swearing, i finally got it through and out the other side. So my old SW is now going to help me keep the foundation of my house moist. :mrgreen: Note that I said earlier that I used black tubing to pull the old water out of the tank. I did, but I ran out in the garage so i had to use a John Guest coupling to attach some leftover white tubing to make the line long enough. Once all your tubing is run to your sump, storage tanks, LM3, Remote Pump, and a drain, you are now ready to program the LM3. The LM3 is very easy to use. I'm not a technical person AT ALL, and I was able to figure it out. The instructions are very easy to follow. Once you calibrate the pumps (follow the detailed instructions) you are ready to tell the pumps how much water is going to be pulled out and pushed back in. So lets use my tank as an example and I'll show you how easy it is to break it down. Note that the LM3 is metric and uses Liters. My tank is 130 gallons, plus about 20 gallons in the sump, so lets just say 150g total. You need to tell the LM3 how many liters PER DAY. So I knew that I wanted to change around 20% of my total system volume per week. That would be about 30g. Divide that by 7 and that comes to approximately 4.285. Convert to Liters and you get about 16.22. I decided that I wanted to err on the higher side so I rounded up to 18 liters. As others have pointed out in the past, when you are doing small water changes every day vs water changes once a week, by the end of the week you actually changed a tiny bit less by doing it daily. So this is why i decided to round up a couple liters. So now you have this number... 18. All you have to do is choose Pump A on the LM3 screen, and set it to 18 Liters. Then do the same for Pump B. Then set both pumps to RUN. Now guess what... you're done! It was that easy! The LM3 will now turn on 150 times per day, pumping out .12 liters (4oz) each time and pumping the same amount back in. So that's it! Mine's been running fine so far. With both pumps calibrated, following the instructions, you should be swapping the exact same amount of water 150 times per day, without lifting a finger! I'll be monitoring the salinity in my display tank to make sure there is no shift over time. There shouldn't be if the new SW supply matches the display tank to start. And now my "water changes" will consist of quickly pumping some FW from one tank to the other and then dumping in some carefully measured salt, every week or two. Vendors I'd also like to thank the following vendors and HIGHLY RECOMMEND them for both purchasing equipment and for tech support. Scott at Aquarium Specialty Scott at SpectraPure Water Purification Products Jim at The Filter Guys Aquarium Specialty has the best prices you will find on the SpectraPure products and Scott goes above and beyond to help his customers. Scott at Spectra Pure is also very helpful and quick to respond. Jim has the best pricing on tubing, they are quick to ship and quick to respond to questions. I get all my RO/DI supplies there. Marine Depot also carries these items but their pricing is a little higher. But if you are shopping there for other items and want to save on combined shipping, you have that option too. Good luck! If you have any further questions I'll do my best to answer them, and I'll try to keep this thread updated with any progress/changes/problems/etc.