Fill Pump Broken?

Hi everyone! This will be my 3rd grow so I am familiar with the device and the process. Last night I was due for a drain/fill and was able to complete the drain but when it came to the fill function it seemed like the fill pump never turned on.

After power cycling the unit a few times and attempting the Fill, I noticed the smell of electrical burning/fried components coming from the front/center of the unit. Kinda in the general area where the nute bottles are stored. Just last week I was able to perform a drain/fill no problem but this time around the pump wouldn’t engage.

So I ended up manually filling the dwc tank with water and once it reached the high float (Day 8/10 Germination) the app recognized this and completed the Fill function. However, no nutes dispensed from any bottle?

This morning I submitted a ticket with support and hopefully we can figure out a fix. Has anyone else experienced a drain/fill pump failure? If so, how is the process to remove & replace it?

Thanks for the help everyone!


I have not experienced this, however I have taken my Grobo panels off doing other things. The pump is located behind the left panel if you’re looking at the unit. It seemed easy to get to so I can’t imagine the replacement would take more than an hour. The nute bottles concerns me as it might mean more than just the fill pump. Good luck, let us know what support says.


Thanks for the quick response @FireGuy! It is odd. Thankfully the drain pump works and I did notice that bottle 2 dispensed a little overnight so that is working as well. Hopefully it is isolated to the fill pump but I will need to work with Support to figure this out.

Stephen’s mentioned in the past that the unit will only dose nutrients after a successful drain and fill. If the fill wasn’t able to succeed then I believe it probably won’t dose them.

Bottles 1 & 2 are checked hourly (not tied to “a successful drain and fill”) which is why I think that one did dispense.

If you put the unit into fill mode, and then manually dumped the water in while it thinks the pump is running, it should disengage when the corresponding float raises (high or mid depending on recipe stage) and then dose thereafter.


Just noticed you are 8/10 of germination. It might be too soon for anything to be dispensed right now!


Good call. No nutes until day 11 I think.

I had a very similar issue! The pump was stopped up from very small root fragments and from the use of Recharge! The pumps are located on the left of the unit if u are facing the front of the unit! The hard part is the diassembly but once u reach pump all u have to do is simply unplug it! It is held in place by a rubber band so it slides out of it. You will need a small set of hobby screwdrivers for disassembly of pump! Hope this helps! @miami5th


Thanks for the help guys!

@vegetato, Yes during the Fill function int he app I poured water into the DWC to simulate it filling itself. once it reached the high float the app said Fill Finished. So I was expecting the #3-5 bottles to dispense afterwards but nope.

In my other unit, same growth stage, it dispensed bottle #5 after the drain fill. That is a generic hybrid auto recipe. This broken pump grow recipe is generic sativa photoperiod.

Update - Been working with Support which has been fantastic! Based on the troubleshooting it appears the Fill Pump failed. Thankfully the circuit board is good.

I took out the pump and noticed it has a burnt electrical smell to it.

Today I should hear back from support and I imagine they will send out a replacement pump.

Anyone else that has inspected their pump, did you notice quite a bit of rust?


Update - Support has been very helpful! A new pump is on the way along with a grow kit for the inconvenience.

I will update once the new pump is installed.


Yes. Most annoying thing to replace as requires removing most of the paneling. But otherwise ok


Update - Grobo sent me a replacement pump plus tubing. Along with that came very detailed step-by-step instructions on how to remove and replace the pump. The process wasn’t all that bad but did take about 30 minutes. The Fill Pump is working now!

Cheers to Grobo Support for helping me!


Glad you got it sorted out man.


Cheers to @miami5th and Grobo Support!

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Did they charge you for replacement?

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No, they didn’t charge me at all for the replacement pump. They even sent me a grow kit pkg for my time. The unit is still under warranty.

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