Planted Tank Automatic Water Change Overview

Time for a long overdue overview of how I set up my Auto Water Change (AWC) and Auto Top-Off (ATO) systems!

First, let’s start off with the major components.

The most important component of my Auto Water Change system is the GHL Profilux Controller, seen here.

In the case of the AWC (Auto Water Change), I created a Timer. 8x per day, the Profilux turns on the AWC pump for a specified amount of time.
The Profilux also controls the ATO (Auto Top-Off). The water level in the tank needs to be monitored, so I installed an optical level sensor.
The level sensor is seen here on the right.

It’s held in place by my magnetic probe holder attached to the back glass, along with my pH and Temp probes. All three sensors are connected to the Profilux. When the water level drops, the Profilux turns on the ATO pump, and then shuts it off when the original water level is reached.

The next major component is my water storage and mixing station.
Our tap water from the city is pretty bad. It’s full of chlorine/chloramines and high TDS. So I prefer to start with a clean slate and make my own RO/DI water. This also makes it easier to always have stable parameters and easier to adjust levels when needed. Our weather is milder here in the south so I have everything outdoors in enclosures just to provide some protection from the sun and weather in general.
Here’s my RO/DI setup. It’s the Spectrapure MaxCap system and mine has the AutoFlush feature. You can find some models on the Marine Depot website or Amazon. Or you can head over to the Spectrapure website to see the full line.

The RO/DI cabinet is mounted on the wall next to my plastic shed that houses my two 60g water storage tanks. The shed is made by Suncast. It has held up very well. It sits outdoors, getting beat by the hot Houston sun all day long.

The RO/DI creates the water and sends it to the tank on the left. When this side is full, I turn valves and turn on the mixing pump to send the water to the tank on the right. Once the right tank is full, I turn valves so that water is circulating out from the bottom, through the pump and back into the top. Next, I throw in my salts for GH/KH/MAG and let it mix for a few hours. Meanwhile, the tank on the left is refilled by the RO/DI, which shuts off automatically when the tank is full. There is a mechanical float valve inside the top of the tank which creates back pressure in the RO/DI and shuts it down.

Push and pull

I needed a way to push and pull water to and from the aquarium. Reliability is key! So I went with the pumps that are used in the medical and scientific industries, able to run 24/7/365 (continuous duty)… Cole Parmer Masterflex peristaltic pumps. These can be regularly found on Ebay. The Masterflex (big one on the right) typically runs in the $400 range for the noisier brushed motor models. If you are lucky it will come with an Easy Load head. The brushless models are quiet but more expensive. In my case, a little noise is fine since they are outside.

The smaller unit is a cheap, steady flow rate model with standard head found for about $99. This is the one I use for my ATO, which pulls water from the RO/DI tank on the left.

The larger MasterFlex is running my AWC using two Easy Load heads. When it turns on, both heads run simultaneously but I have them set up in opposite directions. One is pulling water out while the other head is pushing water in. They are identical heads, with identical size tubing, running at identical speeds. So the amount of water pulled out, is the same amount of water pulled in. This pump is pulling remineralized water from the tank on the right.

The two best things about using peristaltic pumps like this is they pump far. And you don’t have to worry about back-siphon. So they don’t need to be mounted higher than the aquarium.

Now that all major components were in place and ready to go, it was time to get water from the storage tanks to the aquarium.
I ran 3/8″ semi-rigid tubing from the shed, up under the eve of the house, passed the sliding glass doors, and down the other side to the base of the wall. Then I punched a hole to get inside next to the aquarium.

In these photos you can see the water storage shed at the bottom left of the pic (the smaller one on the other side holds some pool equipment). The aquarium is right behind our cat Pigeon (his foster mom gave him that name and we kept it, LOL) at the top right side of the pic.

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Here you can see the water lines coming in through the wall right next to the tank. I have run this type of tubing (usually the 1/4″) through attics, behind baseboard molding, etc. In order for the Profilux controller to talk to the pumps in the shed, I had to run a Cat5 cable and install a GHL Powerbar in the shed that the pumps could plug into. The Cat5 runs from the controller to the PowerBar which has 6 sockets. Now the controller can turn the pump sockets on and off as needed.

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Once inside the house and near the tank, I switched to a more flexible tubing so it was easier to work with. Silicone tubing is nice and soft and stretches right over the ends of the rigid tubing. It’s held in place with a zip tie for safety.

Typically, I’m running these lines to my sump. But this aquarium doesn’t have a sump. I needed to figure out a way to get the water into the display tank and not have it look terrible. After some research, I came across some stainless steel u-shaped barbed tubes used in the refrigeration industry. They come in a 3/8″ size so it was perfect. And they sit right over the glass!

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Here are the current locations.
In the below photo, this is the line that pulls old water out of the tank on the left side. The black cord is from my powerhead.

I had some black flexible tubing laying around that I used as a coupling between the u-shaped tube and a short piece of 3/8″ semi-rigid. This let me extend it down several inches into the water.

The “new” water line and the ATO line are on the right side of the tank.

Since this is where water is being pushed in, I didn’t want it entering straight down. Especially since my soil comes up pretty high on this side of the tank.
So I used some more of the black flexible tubing as a coupling between the stainless u-tube and a piece of the 3/8″ semi-rigid tubing. I heated up the semi-rigid tubing until it was soft enough to bend and dunked in cool water. Now the water shoots out at an angle away from the rear corner of the aquarium. I did this for both lines.

That’s basically it!
This system has been working flawlessly for a couple of months now. All components are pretty much invisible to anyone looking at the tank.
As I mentioned earlier, the Profilux turns on the Masterflex pump 8x per day. It’s running at 500 ml/min and is running for 5 min each time. Approximately 5.25g per day or 37g per week. That’s only 25% tank volume so I may increase it at some point but I wanted to see how it goes. I also plan on doing a regular large water change every few months.

I know this may not be the simplest way of doing this but it works great.
The use of the Masterflex with dual heads ensures that the same amount of water pumped out is replaced so no change in water level in the aquarium.
There are also some nice advantages to doing small incremental changes throughout the day, seven days per week instead of one large change every week. Parameters do not shift. I don’t have to worry about water temp. Dosing is always the same.

Feel free to ask questions if anything isn’t clear.
Hoping this might be able to help someone set up a similar system or at least give you some ideas for creating your own.