Well, it's been a long time since I updated the blog about the sand system. I blame travelling too much (at first), and then the heat of summer (lame excuse). Anyway, I'm sad to report that the sand system is proving to be too much trouble than its worth. After adding in some more river pebbles to the top to try and ease the surface ponding, it was only a couple of days before it started ponding again. I then tried to dig the inflow deeper into the sand, putting it flush against the bottom layer of pebbles. It wasn't two days before one of the beds began to develop a quicksand-like mush above the inflow, and surface ponding began again in earnest. I was initially optimistic and pleasantly surprised, as I was able to increase the inflow to full throttle after I buried the inflow. But, like I said, it didn't last.
Despite the surface ponding, the system works. I just don't like the water on the surface. It just feels wrong. I was able to do a taste test between a sand-grown tomato and a hydroton-grown tomato, and I have to say that the sand-grown tomato was noticeably tastier. My wife confirmed my impression, as well, and hers was a blind test.
In addition, I'm happy to report that our house is finally under contract. If all goes well with our home inspection and appraisal, we'll be closing on 8/15. I'll be sad to leave this place and my aquapondics and everything else, but I won't miss the commute.
In preparation for leaving, I thought I'd put the sand system through one more test. I took out all the fish. There's still some solid fish waste and other junk at the bottom. I've switch the pump to come on only once per day, at noon, for 45 minutes. [EDIT: I'm going with twice per day, once at 10 AM and once at 4 PM, each for 45 minutes. It was getting too dry in there] My thinking is that if the damn things are going to mimic a surface flood, then I might as well try to treat my grow beds as if they were a floodplain. So, this little experiment will see a) how long do fish waste nutrients last when only cycled through grow beds once a day, i.e. how long will that old fish water provide for the plants remaining in the grow beds, and b) how will the plants do with just two waterings per day. My sand beds still have one tomato each, and I also seeded them with cilantro. There are a couple of other random veggies in there still, like cucumbers and sweet peppers. So, there's an array of different nutrient requirements in each bed.
This little experiment may prove extremely important, as it may imply that you can power many, many more sand beds off of one fish tank, when you only flood the sand bed twice per day. Imagine having a single 100 gallon tank, and then maybe 4-8 50 gallon grow beds of sand/pebbles, each getting flooded only twice per day? Sounds pretty awesome, to me, and it would probably mean that you could get the density of fish in the water up to commercial-like levels.
Cascading Flood & Drain Gutterbed
3 months ago