Dosing pumps

NM. I didn't realize how low volume these pumps were. Looks like they only flow a mL or so a minute depending on tube size.

That's why they are great for dosing concentrated micros, and not that great for diluted macros/large tanks.

Adjusting them is easy. As mentioned before, the rpm and tubing diameter can be chosen when you buy them. Any digital (minute precision) timer will allow adjusting the dosing period, and diluting the fert solution you can further fine-tune the amount of nutrients.

I tried looking at Wasser's set up, but most of the pics didn't show and some of the links are dead (Thread started several years ago).

Can you point me to some of the non-showing pics and dead links? I just went through most of the methods and pics showed for me (where pics were posted) and no dead links. I'd like to update if it becomes outdated.

I think I'd like to set this up submerged drip tube style so I don't have to deal with suction or back pressure. Is there anything not obvious I should be concerned about? Air valve for the reservoir, etc?

I suppose I'd need 2 pumps if I want to dose micros also, unless I set up some sort of solenoid switch combo with 2 reservoirs. Also, is head height a concern with these pumps? Im guessing they don't really get backflow with the low rpms they operate at.

Head pressure isn't a concern, but there can be a little bit of backsiphon if the container level is below or above the water level. It is slow, but could be an issue, so placing the setup accordingly can help. I say "could be" because the backflow depends on the tubing material, and might still not be an issue if you dose say 10ml per day and half a ml flows back in addition to that.

Pretty sure you would need two pumps for separate macros/micros. IMO, there are other, cheaper ways to dose macros. See #10 on the sticky.

The first pic in your thread "DIY automated dosing/topoff" doesn't show, which I assume is a pic of your set up. The second manufacturer link doesn't work for me.

Sorry man, still not sure what you mean. Are you referring to the sticky? You are probably talking about a thread that was posted by someone else.

I was curious about backsiphon after reading your original thread. You solved it just by adding a check valve though didn't you?

No, for the one pump that does that I place the reservoir close to the tank water level so there's no siphoning. Another pump with different (thicker) tubing doesn't backsiphon. Would be difficult to use a check valve for two reasons. First, they work better if there is some backpressure that closes the diaphragm (if you use that type of CV). Second, with the low volume and "stuff" in the micro solution they tend to gum up and not close anymore, or completely close and make the whole thing blow up or not dose anymore.

I looked at number 10, but I like the idea of the peristaltic pump because I could use a very small reservoir in my tank stand. I would be able to put a 2 liter container under the tank, and if I was dosing say 50mL per day, it wouldn't need refilled for over a month. Of course this assumes I can make the dose concentrated enough without the fertilizer dropping out of the solution.

I'm not building this tomorrow or anything though, so I'll think about the water pump method a little more before I formulate a plan.

Well 2l isn't a very small reservoir. And you can easily dose 50 ml with a little water pump as well, so there's no difference. At some point you reach solubility limits of your fertilizers, with macros rather soon.

The two main advantages of the water pump dosing are 1) the price and 2) each time you dose the solution is also mixed up which I find incredibly beneficial (for macros).

I'm not grasping some things about the water pump method.

It seems like you're pushing water from a 160 gph pump through a piece of airline tubing. Why doesn't the tubing come flying off? Is there a return line also to alleviate pressure? Isn't this rough on the pump? (granted it won't run for very long each day)

I don't understand why you need nipples on the end of the tubing either. What's bad about the solution coming right out of the end of the hose?

Also, what kind of pump would work well? Are you using a power head, wet/dry pump or some kind of utility pump?


I can see how the water pump method would be cheaper, but the peristaltic pump method still seems easier to build as well as fine tune to me. You're saying check valves wont work though, which presents some new problems for what I was planning. I wouldn't want drain back, or I'd have to account for the volume of the tubing being filled everytime the pump came on. I don't know if these pumps can run dry either.

I would be running my ferts from a reservoir under the tank which would mean head of about 5 feet.