Building a semi-auto Water Change System for my nano

[HeckleFish]

I was trying to figure out how to automate the process using a Bubble Magus dosing pump but that won't work.
I don't want to spend $400 for an established system, so here's what I want to do.
This is for a Fluval EVO 13.5

I'm going to run a hard tube into the tank in a probe holder that will go 25-33% down and use this as my drain line. This will run to the waste container. This way the suction will break and I can't make a mess at the waste reservoir. What I would need is a pump that can sit in the waste similar to the Tunze that powers my ATO. It just has to pull water from the tank instead of pushing it to the tank.
I run most of my pumps on wifi switches in Apple Homekit so I can set an automation that would turn that pump on for X amount of time which I will determine by running it and seeing the time it takes to go from full to loss of suction.
The automation would also power off the ATO just before this so I won't make a mess.
Once the drain step is complete I will trigger the fill pump running saltwater back into the tank. So I'll need a similar pump to push water back in.

I'll place a small ato-type sensor in the tank that will cut the power to the fill pump when it hits the established level line.
The final step in the automation is waiting an appropriate time and the power back up the ATO which hopefully won't kick in any RO and throw off the salinity. I may have to place the return sensor a millimeter higher so when the ATO powers back up it will read the level as too high for safety.

Who makes a pump with a version that can pull water into the waste reservoir and one that can push back into the tank and is just using a power cord?

This sound workable?

I'll probably only run in while I'm there. I just want to eliminate the mess of pulling out the python and having to wipe up water.

 

[chipmunkofdoom2]

I'm not sure if there's a pump that can sit in the waste water that won't require priming. There might be something I'm not aware of though. A peristaltic pump would work in this application, but you wouldn't be able to sit it in the waste water.

I do something a little bit like this. I use Home Assistant and this Kamoer pump on a smart plug. The pump has a few different modes, but I just use the basic on/off mode. I also only use the pump to refill my tank. I do the draining/siphoning myself. Refilling the tank was the most annoying part to me, so I chose to automate that.

Basically, I siphon/drain the amount I want to change manually into a bucket and dump it in the utility sink. I then refill the tank using one of the pre-defined programs I have for the pump:

 

[crusso1993]

I was trying to figure out how to automate the process using a Bubble Magus dosing pump but that won't work.
I don't want to spend $400 for an established system, so here's what I want to do.
This is for a Fluval EVO 13.5

I'm going to run a hard tube into the tank in a probe holder that will go 25-33% down and use this as my drain line. This will run to the waste container. This way the suction will break and I can't make a mess at the waste reservoir. What I would need is a pump that can sit in the waste similar to the Tunze that powers my ATO. It just has to pull water from the tank instead of pushing it to the tank.
I run most of my pumps on wifi switches in Apple Homekit so I can set an automation that would turn that pump on for X amount of time which I will determine by running it and seeing the time it takes to go from full to loss of suction.
The automation would also power off the ATO just before this so I won't make a mess.
Once the drain step is complete I will trigger the fill pump running saltwater back into the tank. So I'll need a similar pump to push water back in.

I'll place a small ato-type sensor in the tank that will cut the power to the fill pump when it hits the established level line.
The final step in the automation is waiting an appropriate time and the power back up the ATO which hopefully won't kick in any RO and throw off the salinity. I may have to place the return sensor a millimeter higher so when the ATO powers back up it will read the level as too high for safety.

Who makes a pump with a version that can pull water into the waste reservoir and one that can push back into the tank and is just using a power cord?

This sound workable?

I'll probably only run in while I'm there. I just want to eliminate the mess of pulling out the python and having to wipe up water.

There are dual head peristaltic pumps. However, those get costly pretty quickly. You could also opt for a less expensive Jebao dosing pump.