sump/refugium help

[striferitus]

So hello everyone first post here wooo.

Down to business I'm really confused on how the siphon lines going to the refugium to fill it don't flood if the power goes out I'm planning on building a 10 gallon refugium for a 75 gallon tank that has some pretty messy fish I already have two filters on the tank I just want a little spot to help with the biofilter since my 2 hujetas are super popes and a large pleco that poops everywhere too.
Just looking for some explication on how the siphon shuts off something like that

 

[Devzev]

Drill a siphon break rite below the water level. I would suggest drilling a few of them. In case one gets clogged


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[striferitus]

Then you would just use a valve to get the gph right?

 

[Aw3s0m3]

That's correct. I drilled a hole right below the water level on the output to prevent it from turning into a suction and a ball valve on the pump to control the water flow


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