Dosing Pump Siphon?

ubiq · Oct 19, 2021

I've read that 3 roller peristaltic pumps prevent siphoning, but 2 rollers may not. Neptune's DOS, expensive as it is, is a 2 roller. Who makes 3 roller pumps?

Gtinnel · Oct 19, 2021

As I understand it any dosing pump should prevent a siphon if working as it should. As long as one roller has the tube collapsed then it shouldn't siphon. I suppose a 2 roller dosing pump does have a higher chance of siphoning because it will usually only have 1 roller collaping the tube whereas a 3 roller pump will often have 2. My dos doesn't not siphon.
There are plenty of manufacturers that have 3 rollers per head, ghl, Red Sea, kamoer, and I'm sure many others.

Gtinnel · Oct 19, 2021

Actually after looking on line at different pumps it's hard to find a pump that only has 2 rollers, most have 3.

Shirak · Oct 19, 2021

ubiq said:
I've read that 3 roller peristaltic pumps prevent siphoning, but 2 rollers may not. Neptune's DOS, expensive as it is, is a 2 roller. Who makes 3 roller pumps?

Depends on the design of the head unit. The DOS head is designed so the roller is compressing the tubing for more than half the rotation of the head. So there is always a roller somewhere compressing the tubing when it is off. Most dosing heads don't compress the tubing for such a long distance around the head so they require at least 3 to keep one roller always compressing the tubing.

mdb_talon · Oct 19, 2021

I can confirm that a three roller pump can siphon also. Especially if you foolishly put your pump and container above the tank :)

Gtinnel · Oct 19, 2021

mdb_talon said:
I can confirm that a three roller pump can siphon also. Especially if you foolishly put your pump and container above the tank :)

Any dosing pump can siphon if the roller doesn't completely pinch off the tube, ecspecially as parts begin to wear out. So as I'm sure you know the best method is to plan it so your pump siphoning doesn't hurt anything. My dos is setup to where if it does leak around the roller (well technically the tube being pinched by the roller) all that happens is the 2 part in the dosing line falls back down into the dosing container.