Isn't this pressure based level sensor? If you gonna diy, you can do that on any of the existing aquarium controller system. The reef angel controller I used before even have that module for sale directly.It also depends on what you want as not all things one can do is the other capable of at this time. So you need to consider that when deciding. Can the Apex do what is in the screenshot below. That is water levels in my three storage containers in the garage. I put them on this page by themselves so you can see which ones I was referring to. Thr readings are in percentage full for each. I believe the Hydros is more DIY friendly.