No air in lines, ah, yes air infiltration was likely seals or injectors needing replacing due to chlorine degradation. So that fixed that.
Currently, intermittent light brown water.
Need to replace calcite/corosex.
Manually regenerating resin tank as could be fouled resin.
 Tue, Apr 4, 2017:
"Now we know I'd been running my MTM tank without the riser tube being secured into the valve. At some point I'd decided to replace my tanks with 10x44 vortech tanks as I like the technology and compared to the 10x47 tanks I'd been using I'd have more headroom in the crawlspace. I wish I had someone to blame other than myself, but I've always tried to do it mostly on my own and I ended up somehow with a Fleck 7000 without the correct part to seat the riser tube."