Monitoring Runoff, looking for tips from people who already do this

[Noah]

Hello Community,

I’d like to start monitoring runoff to see trends in the ppm and pH of the leachate in my drain to waste system. I was hoping some of you could chime in with how you’ve set yours up.

I have tables that all drain via 3/4" flexible hose to a sump basin which pumps when the water level goes above a trigger. I bought the pulse hub with ph/ec sensors and put the sensors into the sump basin, but I don’t think this was working well for me.

The readings I was getting were very unusual and inconsistent. I think because the sump is not fully drained between each pump down, there is always a fair amount of poorly oxygenated sewage basically that is contaminating the readings.

Ideally, I’d like to be able to tell not just what the runoff trend is, but when it started and stopped. I assumed that I could tell based on the trend when runoff occurred because the trend would go from being smooth to having a jump to a new ph/temp/ec.

I think my biggest problem is knowing how to best fit the sensors onto a drain line etc so that I don’t leak onto the floor and also always get the freshest runoff (so minimal retention in whatever is holding the sensors).

For those of you who have already geeked off on this I’d love to know your setups, especially if you have photos. Thx!

[tosi]

Hey @Noah,

A sump basin would definitely not be ideal for the reasons you mentioned-- if the probes are sitting at the bottom of a non-circulated basin, then you will always have particulate buildup that will inflate off your actual readings. The best way to set them up is inline (shown below) closer to the fresh runoff source. The vertical orientation keeps the pH probe wet between readings, and it takes a very small amount of runoff to completely ‘refresh’ the sample runoff for both sensors.

EC sensors don’t need to stay wet, so you can cut your PVC to the perfect length so that it will only show 0EC until the runoff event happens which then submerges your sensor, and gives you the correct readings for that particular irrigation. This way you can very easily see the change on the historical graph, you’ll get the jumps/trend you are looking for.

The fittings are standard 3/4" threaded PVC from Home Depot. The pH sensor threads directly into a 3way tee, and the EC into a 3/4" to slip which then connects to a tee as well.

[Noah]

Thanks! That’s exactly the sort of answer I was looking for.

I think the only reason that might not work exactly as described in my situation is because the runoff is fairly gentle/slow on my 8’ tables, so it would be unlikely to raise in the pipe more than just a little bit. You’re right, it would have to be tuned just perfectly to only get submerged when the runoff was happening.

I think a way I could potentially enhance that tuning would be by having a multi-orifice drain, one that drained slowly and one that drained quickly. That way it would fill up a chamber rapidly even with a small flow, but still be able to completely drain when the flow stopped. Perhaps something like this:

I just wish my idea wasn’t so bulky as to put a torque on the drain attachment point, and wasn’t so likely to clog with just a little bit of coir dust or whatever.