In the process of rebuilding Greenhab (the first was destroyed when I tried to use the dishwasher to clean it, only for it to partially melt) I decided I don't want it to be a single use gimmick. I want it to really work, and be able to stay down permanently.
Two problems with the last one: 1. too cold, and 2. no way to water the plants without bringing it up. I solved 1 by adding resistive heater pads.
They may or may not be too warm, if so I can add an inline potentiometer to throttle how much current they receive. I thought I'd solve 2 by adding a second tube just for water.
But, I hate adding extra surface connections, Quickly becomes an ugly, unmanageable tangle. Instead, I've worked out that I can simply inject water into the existing airline, letting the compressor push it down to the plants. This means Greenhab 2.0 will never need to be resurfaced.