Well on the morning check I found the CF=28 which is a clear indication of a lot of transpiration without uptake of nutrient and the level was down. We've had a hot couple of days and the plants are getting quite large. I topped off the system and checked the nutrient level. It had dropped to 19, so based on the observation that a quarter cup of concentrate elevates the nutrient level about 2 points I added a half cup. I'll check a little later to see if that took it to 23 which is what I expect.
A little later has come and gone and the equilibrium seems to be about CF=22 so I'll add another quarter cup of concentrate later. So in summary I topped the system off on the 25th and now on the 29th I topped it off again so it's running down in something like four days in the current weather. Still from the standpoint of maintenance this has been the least work of any system so far. It's also pretty safe since you don't have to worry about power failures since all that does is turn off the oxygenation and circulation pumps or a while but it doesn't keep the plants from getting nutrient which happens in my NFT systems.
This has me thinking about how float systems could be enlarged and improved. I've done tubs in the past and they worked especially well for things like lettuce and basil. So far this float system is working well for tomatoes, although I'm still concerned that as the fruit set and the plants get heavier that the weight will sink the floats and the support system, which was improvised from tomato cages, will prove inadequate for its use. We'll see. That's one of the fun things about being a hydroponics hobbyist.