So what are the differences ?
CRAFTS - Constant Return Aquaponics Feeder Tank System make use of Growbed over the fish tank method that some may say an obsolete system. "Growbed over Tank" is a proven simple system and there are still life left in this system in the form of modular CRAFTS.
This system make use of Return Tank which is under each Growbed and over flowing into a common Feeder Tank which then feeds water to Growbed using pumps.
One or more pumps can be use depending on water feed requirement. Pump don't need to be anything special, a simple pump will do. No requirement for float switch activated pump.
CRAFTS multiply in modular Node, each Node comprise of Growbeds over a Return Tank which in turn over flowing into a common centralize Feeder. Water volume will increase as more Nodes is added.
In CRAFTS each Nodes can house different fish species or it can be use as Nursery or Breeder Tank.
CHOPS - Constant Height One Pump System it also was called CHFT PIST which make use of growbed over a sump tank and a higher Fish Tank that gravity feed water onto Growbeds.
The taller fish tank in CHOPS will ensure enough water head available for growbed and an over-flow will ensure Constant height of water in this tank. It make use of one pump located in the sump tank and for safety reason it must be of the float activated type, just in case the sump is low in water.
All water is within this taller fish tank and it will need to take into account of number of growbed needed to be feed. Expansion of system is possible by adding more growbed and increasing the fish tank size if its not able to accommodate water requirement.
Growbed which are further away from sump tank may need its own sump but that will no longer be a One pump operation.
Above are some of the difference between CRAFTS and CHOPS both this system will have constant level of fish tank water making it better for fish in reducing water fluctuation stress.
Usage of either system will be dependent on individual preference and space availability. Installation that is not subjected to space constrain and planned ahead CHOPS can be use, if a modular approach is important give CRAFTS a go.
In all, both these system add to more ways we can practice Aquaponics and its suitability will depend on individual installation requirements.