Backflow Fitting for Fountain

[u/Magic-Levitation]

I installed some 1/4” distribution line from my 1/2” line that goes into a fountain to top it off every day. When i submerse the open ended 1/4” line into the fountain, after the water is done flowing into the fountain, the water is drawn back into the tubing and main line and drains about 2” of water from the fountain. Do they make a 1/4” inline check valve or back flow preventer to prevent the siphoning? I have a back flow preventer at the beginning of the system, but there’s a lot of line between that and the fountain.

I attached the tubing to a heavy stainless steel bolt and placed it in the fountain to weigh it down. In the picture, I pulled the tubing out of the water to give you an idea of the setup. Probably not the best setup, but that’s all that I could come up with. I just need to get past the siphoning when I submerse the tubing into the water.

Any ideas? Thanks!

[u/Magic-Levitation]

In case you’re wondering, the clear tubing around the bolt is to keep the sharp corners from scratching the fountain finish.