Drain & Fill Water Changing Method, Step by Step
I currently use the Drain & Fill method to change all water in my tanks. I prefer it because it wastes the least amount of water and doesn’t require drilling tanks or building/buying overflow boxes. There are many ways to drain & fill a tank, it ain’t Rocket Science.
For my 180g tank I bought 2 Rubbermaid containers that hold 18g each. One is placed under the tank stand and it holds the water while it is aerated & heated. There is a small water pump in that container that I use to refill my tank. When I do a water change I would siphon water from the tank into the 2nd Rubbermaid, while refilling the tank from the holding tank. The rate of flow from my siphon & the water pump were pretty much the same so when I had filled the 2nd Rubbermaid the first one was empty. Then I’d just refill the holding tank and it would be ready for the next day. This is not technically a drain & fill method since I’m doing both at the same time but I’ve since altered this method. I only discuss it here as a method for tanks that are not near a sink or drain.
Recently I bought a 185g holding tank for my fishroom. This has allowed me to perform 50% daily water changes on all of my tanks. I still have a 70g holding tank as well and use it for mixing RO & tap water for breeding tanks. If there is no breeding activity I still add some RO water to keep the membrane moist and fill with tap water and use this for water changes as well.
When I only had 8 tanks in the fishroom I would siphon each tank to the level I wanted and then I just had a hose coming from my 70g holding tank and I’d move it from tank to tank as I refilled. It worked well but I found that much of the time spent on water changes involved waiting for tanks to empty and then waiting for them to refill. The actually work of siphoning took very little time. I recently added 4 new tanks and the larger holding tank so I had to come up with a better way to do this task.
The starting point was to build some siphons. I had these PVC units built from a previous project so I just cut out the pieces I wanted. This unit is simply a couple of J tubes with a hose attached to each one. The one of the right goes in the tank and the add’l bits on the end are just to lower the water level a bit more. I could have also added a pipe connector and just attached a bit more pipe but I had these pieces. When I do a water change I just run a siphon like this to each tank and give the other end a suck and hook it on my sink. It takes about a minute to get all of my tanks draining. It was definitely easier then drilling tanks and putting fixed drain lines in place. While the tanks are draining I go from tank to tank siphoning the bottoms.
Rather than moving a hose from tank to tank for refilling I decided to use 3/4″ PVC pipe to direct the water. The pipe runs over or below each tank and then has a ball valve at the tank to control the water flow. I have a Mag Drive 1800 water pump inside the 185g holding tank. It can be tricky running this pipe and some thought should be given to the optimal position for the pipe line. This picture is an example of the pipe that runs above a set of tanks. Since my tanks are stacked 2 high there is a hose that runs down to the lower tank and is then attached to the tank stand so it does not get directed away from the tank. I have hoses on the ball valves for the upper tanks so the returning water does not splash on the surface. These hoses are removable but so far I’ve just left them in place.
For tanks that are attached from a pipe running below them I just ran a hose up to a PVC J tube. I even ran a PVC pipe over the top of a 30g tank to get to tank next to it. I had to do it this way because the pipe was running beneath the tanks and I didn’t want to run it up the front of the tank. And all of my tanks are pushed back against the wall so there is no room behind them. It takes some concentration to refill the tanks while siphoning others. You have to remember which are refilling and turn them off before overflowing. But doubling up on the chores makes the whole thing go faster. I plug the water pump to whichever holding tank I’m pumping from (or both) to a power bar and just turn the power bar off & on if I need to stop the refilling. But in the end I have to turn on & off ball valves as well.
As I mentioned there is a Mag 1800 sitting in the holding tank. I had to buy one fitting to connect the pump to the bulkhead fitting on the tank. The hole was drilled as close to the bottom as possible so the pump is able to just sit on the bottom of the tank. Then I added a Y adaptor with a shutoff valve for each connection. The one hose goes to my tanks, the other is available for refilling my 180g tank, which is in another room. It’s important to have some sort of shutoff valve at the tank opening so you can remove the hose and tip the tank for cleaning, as well as to guarantee there is no backflow from the tanks. Remember that if the J tubes going to each tank remain submerged after refilling they all have the ability to start siphoning after you’re done. So I make sure I turn off each ball valve after I’m done with a tank. The holding tank sits on a piece of plywood so my concrete floor doesn’t act as a heat sink and cause a significant heat loss.
For refilling of my holding tanks I have some ball valves to allow me to fill them one at a time. At one time I ran the water through a sediment & carbon filter but I had to run water so slowly that it took forever so I removed the filters.
When I refill the 70g holding tank I am cleaning up from doing a water change, putting away siphon hoses etc. so I just refill it while I’m there. But the 185g holding tank takes about 30 minutes so I built an alarm to warn me when it’s full. It’s just a water detector made by Zircon that I’ve attached some wires to and threaded through some acrylic to keep them apart. I hang this on the holding tank while refilling and then leave the room. When the water level rises to about 4″ from the top the alarm goes off and sounds like a smoke detector. It works great, so long as you’re within earshot. I considered getting a solenoid & float switch but this hobby costs me enough as it is so I saved some cash & just used the alarm.
So I now do 50% daily water changes on up to 700g worth of tanks. I say “up to” since I typically have 3 or 4 empty 30g tanks. It takes about 35 minutes to change water in my fishroom and then later that morning I do a 50% change on the 180g tank. That tank takes little actual “time” as most of the time is just waiting so I get other work done. I run a hose from the 180g to my house sump and drain half the tank, while siphoning the bottom into the Rubbermaid container. Once it’s drained I just move the hose to the barbed connector on the holding tank and refill. Then refill the holding tank and it’s ready for the next day.
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