I have a problem with my new (first) system. My fish tank is a small ~30 gallon. My bell siphon wont start unless I allow a flood and drain cycle of only ~6-7 minutes. If I reduce water flow the bell siphon won't start. I want slower flood/drain cycles.
I wonder if this could be easily solved by adding a timer to the pump? Pump on for ~30 minutes, pump off for ~30 minutes. I have a small 4mm drainage hole at the lowest part of the standpipe so the water could drain even if the pump turns off.
Is this a bad way of solving the problem?
There is not a problem with a 6-7 min cycle, just a little more noisy. You could use a smaller diameter standpipe for a longer drain period and lower fill rate, but you may not achieve enough suction to lift all the water in the bell.
pump on for as long as it takes to flood the bed - off for as long as you want, within reason, keeping in mind aeration and filtering
Depending on the size of your bed 6-7 minutes might be fine. You want to turn the tank water at least 2 times per hour. If you're doing 6 minutes per cycle then you are getting 10 cycles per hour. If your bed holds 10 gallons of water then you're doing 100 gallons per hour or about 3 turns of your tank which isn't a bad rate.