Picture of Hydroponics Float Valve
Do you want to keep your reservoir topped up without hassle?
Don't want to buy an expensive float valve?

Make your own!

I have been building a hydroponics garden, and I wanted to make sure my reservoir doesn't run dry and destroy my pump (or kill my plants), but a side entry float valve would have cost me $30+ at the local hardware store, and I had already spent my budget on pipes and plants.

So, calling on my childhood obsession over MacGyver, I looked for what I had lying around, and built a cheap and surprisingly effective float valve! (effectively for free!)
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Step 1: Disassemble

Picture of Disassemble
Start with opening up the sprayer.

If you look at the spray end, you should notice it looks like an inverse nut.
Push your pliers into the corners, and turn like a screw, it isn't hard to get undone.

When you have the front off, unscrew the small plastic nut from the other end, and slide out the innards.

Step 2: Mod and reassemble

Picture of Mod and reassemble
See that spring?

That is the one thing holding us back (it is way to stiff, and we don't need it!).
Simply slide it off.

Now, without the spring, there is nothing holding the plastic shaft to the handle, the shaft will happily go in to the open position, as the nut is pushed up by the handle, but it won't push back in.

I found a small rubber thing (picture 2) laying around, so I drilled a hole in the centre, and used a grinding bit on my dremel like tool to make it shorter.

This fit perfectly on the shaft before the handle (it actually 'screwed' on!).

Now when the handle goes down, it pushes on this bit of rubber and the shaft goes in as expected.
kerisa1232 years ago
just use a ball cock from a trough
fearless775 years ago
Wouldn't a valve from the toilet system be just as good?
NathanWilliams (author)  fearless775 years ago
Yep, except that would cost money, I had the hose attachment come with the hose I used for the system, so it was basically free! Also you need to get a specific toilet float valve, one that fills from the side, instead of the more common filling from the bottom.
elskeetro5 years ago
Killer idea and execution. I just build an auto top off using a toilet ballcock kit. It works well but is very slow to fill. I wish i had found this first. I'm gonna build it any way. Thanks!
jaskohl5 years ago
The purpose of this is a bit confusing to me. Why not just use a larger bucket? I had a similar setup with a 18 gal. Rubbermaid container for the reservoir. I like your solution for the screens. That was the one problem I had was that the roots clogged the hose and flooded the top tube and dried out all the others. Killed the whole crop. Great instructable!
chefmichel6 years ago
Excellent idea, good instructable. Nice and clear pictures. McGyver would be proud of you !
NathanWilliams (author)  chefmichel6 years ago
As a kid, I believe that was my dream =D
crapflinger6 years ago
nifty indeed...i've seen people use toilet parts for this kind of thing...which are easy to acquire
NathanWilliams (author)  crapflinger6 years ago
Ahh, at my local hardware store they wanted $30 for the float valve, this was free!
I saw that in your other instructable and didn't "get it", now I do, cool idea.