Automated Water Changing

Anyone who changes water in a fish room with hoses and buckets dreams of automating water changes.  I wanted one for years, and when I moved the fish room to its current building two years ago I finally installed one…. and it is a real game changer.  If it were not for the water changer, I would not have enough time in a day to maintain all the aquariums that I have.  An automated system is well worth the effort to install, and they are not very expensive.  The hardest part is drilling all the tanks, but there are ways to do it without drilling.


Here is a transcript of the video:

Water changes are the most labor intensive job in a fish room. The larger the room, the more time it takes. Most of us want to automate as much of the task as possible. I would not have the time to keep up with water changes in my fish room if I had to do them all by hand. This video will show you how I manage the task in my fish room.


Water Softener

Before we get to changing water, take a look at these two sponge filters. The filter on the left has been calcified but high general hardness in my tap water. The filter on the right is what a clean filter with no calcification looks like. The calcium and magnesium content of my tap water is so high, that when I opened the fish room all of my filters looked worse than this in less than two months. Huge problem!

I had to solve this problem by installing this 98,000 grain water softener onto the main water line into the bulding, which removes most (but not all) of the general hardness from the water.

This water softener exchanges most of the Mg and Ca general hardness for sodium chloride. Using water parameter terms, before the water softener the GH of the tap water is 18 – 20 degrees of hardness and about 480 parts per million total dissolved solids. The KH before softening is 14-16, and the pH is about 8.2. After passing through the water softener, my tap water parameters are GH 6-7, KH 5-6, pH 7.4-7.6 and about 300 parts per million TDS.

But most of those dissolved solid particles are sodium chloride, which does not bother fish in such low amounts. When you treat your tank with aquarium salt at a rate of one tablespoon per ten gallons, you are putting a higher concentration of salt in the water than I get out of my water softener. That salt has the added benefit of discouraging parasites like velvet and ich… salt is not a cure for those diseases… but the salt can help prevent the parasites from getting a start. That is a topic for a future video.

Another advantage to the water softener is that it removes the chlorine from the water, so I do not need to add water conditioner when filling tanks. My water utility does not add chloramines, and I am not sure if the water softener would remove that molecule.

Most homes are not using a water softener on the main line coming into the building like mine is. Typical water softeners are only plumbed to the hot water line, and the cold water is not being softened. Keep that in mind if you have a water softener in your home… only a portion of the water you are running to your tanks will be conditioned.

Automated Water Changer

My fish room is divided into two areas. The main section contains 176 aquariums that are connected to an automated water changing system. The other 52 aquariums are not connected to the water changer.

Water flowing to the automated water changer comes through this dedicated tap, which has both hot and cold water spigots so I can adjust the temperature of the water. My cold tap is far too cold in the Winter, and I have to add hot water to the flow.

The water passes from the tap through these prefilters: two sediment filters and one carbon filter. Note the discoloration on this prefilter. Even with my 98,000 grain water softener, a lot of crap, especially iron, is making it to this point in the system. I need to change these prefilters once a week, and you can really hear the difference between the water flow through filters that are new and those that need to be changed.

The manifold for the water changer itself has a solenoid control valve at the back end. These valves are sold for lawn and garden irrigation systems. The valves are controlled by a lawn and garden sprinkler system control panel, in this case a Rain Bird unit. Each valve feeds a separate zone in my fish room, which I will describe in a moment.

Here is a tip for planning your fish room… buy two times the number of valves you will need for your system. Valves can go bad, and finding one that will fit your manifold may be impossible 2 or 3 years after you set the system up. If you buy them in the Fall, most stores that sell them will have them on sale. I bought mine on sale at a large hardware store for about $10 per valve.

After the solenoid valve, the water passes through a check valve, which prevents water from flowing backwards through the system. This is not a big problem for my changer because path of the piping goes from the manifold to the ceiling, so there is really no way that water can flow via gravity past this point anyway. The check valves are making sure that there is no fluid backpressure on the solenoid valves, which can shorten the life span of the rubber seal in the valve.

After the check valve, the water passes through a pressure regulator, which reduces the tap water pressure to 30 psi. The pressure regulator is absolutely required if you are going to be using small emitters over the tanks. Without the reduced pressure, you risk breaks and leaks in the system.

Above the pressure regulator is a disconnect where I can separate the valve assembly from the line. Do not forget to use this connector. You do not want to have to cut your water lines to replace a bad valve.

My fish room has four zones that are separated by the size tank on each zone. All of these 30-gallon breeder tanks are on zone 1.

Zone 2 has all 10-gallon tanks. Zone 3 has all 15-gallon tanks. Zone 4 has all 20 gallon tanks. I set it up this way so that each aquarium in a zone will get the same percentage water change when the system is running.

Each aquarium has a 10-gallon per hour valve overhead that flows water into the aquarium, and an overflow bulkhead through which water will leave the tank. The overflow drains through flexible tubing to a drain pipe at the bottom of the rack. The pipes run around the perimeter of the room and into a floor drain in my tap room.

All of these tanks get 1/3 of their volume in new water three days each week. The 30-gallons in zone 1 will get 10 gallons of new water through the 10-gph emitter, so the timer on the system will run for one hour on the days that this zone gets a water change. But one hour is too long, and I will run out of hot water, so I break that one hour up into four 15-minute periods separated by two hours. The amount of water changed is small and spread out over 8 hours. All of the zones are set up this way.

The Other Aquariums

The tanks that are not on the automated water change system cannot be plumbed easily to the water changer. Someday I will come up with a way to get this side of the room more automated, but it is not a priority. These tanks have been shifted around three times since opening the fish room, and I am still not 100% happy with how the space is being used.

Water changes on these tanks require siphons, hoses and time, but they are not so many tanks that this is a big problem. I also try to use these tanks more for breeding than the tanks on the water changer, because breeding tanks contain fewer fish and do not need water changes as frequently.

One difference on this side of the room is that I plumbed these aquariums for drain and fill water changes. I can turn this valve and walk away as the tank empties, close the valve when the water level is at the amount of water change I desire, and then refill the tank.

Drain and fill is better for breeding fish and raising fry than a flow through water changer, because drain and fill is perfectly efficient. 100% of the water leaving the tank is old. The water changer is less efficient, because some of the new water entering during a water change will also leave the tank during the same water change. Those larger, 100% efficient water changes are better for breeding and raising fry, because the growth inhibiting chemicals which accumulate in old water are more completely removed.

Special Water Parameters

Keeping fish healthy and breeding them are often two different issues. Most fish can happily live in most tap water conditions, but require more specific parameters to successfully reproduce. Soft, acidic water is the most common type of water that we need to recreate. If your tap water is as hard and alkaline as mine is, the only way to truly drop the hardness and pH is to use reverse osmosis.

My r/o unit has two membranes and is rated at 180-gallons per day. I am not going to go into the details of my R/O machine in this video, as that is a topic for another time. I store reverse osmosis water in these 250-gallon carboys, and distribute it to the aquariums with a hose and a pump.

Access to Drain Pipes

When you design your fish room you will probably want to put all of the pipe for your water changer behind the racks. You should also build in a way to access the drain system from the front of the racks. These pipes at the bottom front drain into the same system as the automated water changer, and I use them to siphon water from the tanks for special maintenance tasks. The fewer buckets you need to carry the better.


My fish room still has a lot of hoses and buckets, and even with the water changer I spend a couple hours every day on general maintenance, manual water changes and solving problems in the fish room. The automated water changer provides that time. Without it, just doing the water changes would be a full time job.

10 Replies to “Automated Water Changing”

  1. Ted, I am setting up a fishroom in my garage and was going to use wooden racks like yours and a similar water changing setup, I was wondering though how much space you have behind your racks to work in? I want to be able to get back there but I don’t know how much space is necessary and wanted your opinion.

    1. Hi Will,

      Depends upon how much space you need. I am a big guy, so I left about 18 inches between the back of the rack and the wall.

      1. Thanks Ted!

        Where did you get your emitters from? Most of the ones I see only have a couple of gallons. It also looks like you used PVC to transport the water instead of the flexible black irrigation tubing, was there a particular reason?

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