Hi all, about 2 -3 months ago I posted a thread on here about moving to a location where all I have access to is rainwater for my fish tanks. I got some great answers and help, but I'm back to ask for more ideas. So currently, I have three tanks, 2 2ft and 1 3foot tank. The info I got from my previous thread post lead me to get seachem equilibrium to increase my gh, and tiny shells to increase my kh. So far this has worked pretty well, but takes a bit of time. I'm in the planning process of building a fish tank rack filled with 9 2foot tanks, and have decided to develop a semi automatic water change system to make maintenance quicker and more enjoyable. The water change system will follow the dilution method of dripping water into the aquarium at a set rate, which will push some of the old water into an overflow, and the rest of the new water will mix with the old water. My current method of water-changes with the three tanks I have is draining the old water, getting fresh rainwater and mixing in the seachem equilibrium into the water in a bucket to achieve my desired gh. Then I add it to the tank/s. My though process is that if i want to follow this same method for the upcoming fish rack then i would need a middle man (watercontainer of some sort) which I would need to add the correct dosing of equilibrium. From that middle man I can then pump the water into the tanks. My question for you guys is if there is any way to make this simpler? Can I add crushed coral or a material like it to the tank to handle both gh and kh so i can just pump in fresh rain water? I might have missed something but if you have any questions feel free to ask. Thanks in advance.