Slugs, millipede, centipede, ants and other crawlies can start to be comfortable in the growbed.
How do we get rid of them ?
On flood and drain media base aquaponics, I recommend to flood the growbed. Most crawlies can't survive underwater for long period.
To flood the growbed first stop the siphon action by removing the enclosure bell as photo below.
or remove the siphon cap on the #strainerbell siphon as below,
Once the cap or bell has been remove, the siphon action will stop. This depends on the height of standpipe will cause the growbed to be flooded. If the standpipe is lower than the media height, it is advisable to remove some of the media or change the standpipe extender to a longer extender causing a flooding.
Downpipe photo of the siphon as below with replaced extender.
Once the growbed flooded, wait a while and you can now see many creepy crawlies start to make their way to the top of the growbed. This is a good time to get your slug picking chopstick ready and start picking.
and more slugs
Well have fun picking those slugs.. :)
How to get rid of ants ?
For ants, I recommend that the high water extender are left there for a few days, and let the siphon operated as normal. Then replace it back to the ones that have water 1" below media height.
I recommend doing this flooding monthly, to ensure slugs etc don't have time to multiply. It is such an easy thing to do anyway.