Doser Pump Siphon

JamesP · Apr 14, 2017

Im in a situation where I need to move my dosing equipment out of the sump on to the top of my hood where it is out of sight. I need the space below for some modifications I need to perform to get a refugium up and running. I explained to my wife that it puts me at risk of a siphon forming if the dosing vessels are higher than the output of the dosing line but she said I cannot put the vessels on a shelf lower down because they would be visible and no matter how pretty I said id make it she said no.

So what I came up with is I need something to act as a siphon break. I am using BRS 1.1mL/min dosing pumps. I know in theory the pinched tubing makes a siphon an unlikely scenario, it is still physically possible in this arrangement. I have an idea I wanted to post to see what other people think.

First, its important to understand the pumps themselves are the highest point in the system. They will be on the wall above the hood. Vessels will be below, but on the top of the hood. I was thinking if I got a 1/4" tee and put it on the output side of the pumps with the tee arranged so it can drip straight through and the third opening of the tee faces to the side. I was then looking at putting a stem elbow in the side tee opening and facing it upward. I figured it would drip slowly enough not to come out the side but the opening would prevent a siphon.

Any thoughts on this from the community would be appreciated.

JamesP · Apr 14, 2017

Im looking around brs thinking about this and I had a cheaper idea that does the same thing. I could use a tube divider right on tbe output of the doser pump, but installed upside down so the double end is up and the single end is down. Doser would drip through the fitting and couldnt form a siphon because of the other open end that faces up. It seems like it would be perfect.

200501-Reverse-Osmosis-Tube-Divider-1-4-inch-QC-a_1.jpg

JamesP · Apr 21, 2017

If anyone finds this later, it worked very well. The splitter is acting as a siphon break and is above the highest fluid level in thr reservoirs. Dosing amount is accurate and all tubing below the splitters are as vertical as possible to avoid and standing fluid in the lines.

reefwiser · Apr 21, 2017

Question so you have this on the output line?

sundog101 · Apr 21, 2017

I wouldn't think the brs pumps would back siphon. I'll have to watch mine more closely.

Is it siphoning into or out of the tank?

JamesP · Apr 21, 2017

Yeah its on the output and above the fluid level in the reservoirs. So basically it pumps upward and then trickles downward via gravity on the output side. The dosers aren't supposed to siphon but a google search found folks with the same 1.1mL/min with slow dripping siphons in some cases so I wanted to make it 100% impossible. Also as the pump ages, it would run a higher chance of the rollers not pinching as tightly. I just didn't want to take any chances since my resivoirs are above my tank and if the pinching of the rollers is less than perfect even at a later date, a siphon is now impossible.

JamesP · Apr 21, 2017

sundog101 said:
I wouldn't think the brs pumps would back siphon. I'll have to watch mine more closely.

Is it siphoning into or out of the tank?

Its not to protect against a back siphon, its to prevent a forward siphon since my resivoirs and dosers are above the tank. I protect from a back siphon by keeping the ends of the tubes above the water where they drip into the tank above a powerhead.

pboutin · Apr 21, 2017

I had this problem on my 5ml BRS doser. What I did was add a check valve off of a air line T above the pump on the fluid out side to allow air into the line but not out. This acts as a siphon break. The fluid in the remaining out line does not tend to flow freely out as it doesn't weigh enough without a siphon to "fall" out.

JamesP · Apr 21, 2017

I almost used a tee but fear of it squirting out the side leg of the tee made me go with the splitter instead because the shape of the fitting is more resistant to that. A tee with a check valve is essentially the same thing, with the valve to mitigate the potential of squirting out. I thought about adding the check valve just like you, but when i saw the splitter it seemed like a simpler solution with less parts and no moving parts.