DIY AWC system

[yoelf]

Hi,
So I when I find a new hobby I typically go all in get creative make projects a little more complex than they probably need to be I'm pretty sure this might be one of them lol
Also at first I didn't think I would be getting so deep into the hobby but the more time I invested the more I find myself intrigued by it this is the reason why I only have a 40gl breeder and equipment the costs so much I got the tank my first week into the hobby and before this past month is cheap stuff like my fluval skimmer this past month when I really got into it I bought the BashSea SS-30 sump full Apex COR-20 hired a professinal to make and design my rock aquascape (not as expensive as you might think) buying life rock by the pound is expensive this isn't and I got it personalized to where I have a zoa garden and a nice place for my future chalices.
I'm planning on getting the Neptune's DOS and use the first pump head to take water out of the skimmer section of the sump and outside to the grass and have the second pump head taking fresh circulating saltwater from a brut container outside into the return section of my sump while being creative and concealing the tubing thus creating a slow but very consistent water change.
I ran this by my boss (He has a PhD in marine biology) his main concern with my completely unnecessary AWC system is that even though both pumps are one unit in his experience one doser would probably be ever so slightly off and with time compounding making either:
1) Taking more water than it's gaining
2) Giving the sump more water than is being taken out
For this a simple failsafe would be to watch the water levels in the sump and the container or implement a sensor in the sump if the water ever got past a certain level I would be notified.
If anyone has any experience with something like this and can save me time and give me tips on logistics would be appreciated.
Thank you

 

[Jimbo7]

If you do a bit of searching on AWC systems here you'll find a lot of information. The DOS system seems to be fairly consistent between the two pumps and your margin of error would be pretty low with any decent amount of water being taken out without getting too complicated.

However if you didn't want to go the DOS route, I know its very common to use two general dosing pumps attached to a controller with high and low float valve sensors. The high sensor is usually the water level sensor as well and people calibrate the distance from the high to low to equal the water they want changed. Basically the OUT pump runs until the low sensor is triggered, and then the IN pump runs until the high sensor is triggered.