Room flooded! Please help!

Hi everyone. I am using a drip to waste system that jas been working perfectly fine. I have a 100l tank and the plants are fed using an mj1000lh pump. I usually fill the tank to aboit 80litres. Now ive had no problems till the other day. I came home to find the room flooded. So after a clean up operation i turned the pump off because the plants were saturated and certainly wouldnt need feeding that night. Whilst in the room, i topped the tank back up. Now the pump was OFF but the next day the room was flooded again! The tank was emptied to about half way, same as day before. Whats happening?! This hasnt happened before. Has the pump become weak and the pressure of the water above forcing the propellor round? Is it siphoning out? Please help becuase i am lost! Ive borrowed a pic i found online which is exactly what i have but i have 8 plants....Help!
Thanks in advance.

Could have a hole in the reservoir somewhere. If that's not the case the pump might not be shutting off / closing. Based on your diagram if gravity is allowed to push water then it will flood through the plant pots.

If you are certain that there are no leaks in your system then the likely cause is siphoning. If there was still water in your lines when the pump was turned off then the drainage of those lines could be enough to siphon the water out of your reservoir. This would continue until the level of your reservoir was equal to the level of the drip line outlets.

You can fix this problem by adding an electronically controlled solenoid valve (normally closed) to your system and run it on the same timer as your pump. That way the valve is only open while the pump is on.

You need a vacuum breaker on the outlet side of the pump. What's happening is that the pump runs its cycle but the reservoir level is higher than the irrigation system. This means that when the pump shuts off water will continue to siphon until the res level reaches the irrigation system height.

The way to fix this is with a vacuum breaker, or at least a tiny hole somewhere in the line downstream of the pump. These will let air into the line when the pump shuts off and keep it from siphoning off your res.

what tty said

personally I am not a fan of pumping water to something with a lower flood level than the res, shit fails, you want it foolproof

drill a little hole in the main line so a little water sprays inside your main reservoir. Right above the water level and inside the reservoir is where to put it. this will discharge the pressure inside the line once the pump turns off. Easy, cheap fix to siphoning.