Got out to the farm and AP set up Thursday. Earlier in the week, I tested gravel samples from four different quarries for their effects on PH. I just put some gravel in a small container and added tap water. I tested the PH of the tap water before adding it to the rocks, and a few hours after adding it. All samples caused the PH to rise. This could be do to residues left on the rocks and may not necessarily mean they actually contain limestone. In order to determine whether the PH effect was due to residues or to the rocks themselves, I brought the PH in all samples down to 6.0 by squeezing a little lemon in each container. Then I waited a day t see what happened. Two of the samples held at 6.0 and the other two rose back to above 8.0. Counting the gravel I'd already used in the system, that means 2 out of 5 quarries produce rocks that won't raise my PH.
Unfortunately, this means I have to haul gravel from the city all the way out to the farm, in my truck. I took 300 kilos out yesterday and am sending a truck with the rest tomorrow.
The plants are doing remarkably well considering they're living in the PH equivalent of Mars. Alright, I know they don't look good, but I am just surprised they are standing at all. The squash (lower right) has about doubled since Sunday. The other have grown a bit, though I haven't taken actual measurements.
The plants in this bed aren't doing as well. They are the ones that suffered through the siphon-failure last week. In any case, I'm happy they're even standing!
Since I have to change my gravel anyway, I've also decided to make a major, but I think worthwhile change to the system. Right now, my beds are higher than my tank, and they drain into the tank. This is OK, but the beds are pretty high up. The tables they sit on are 70cm high, and the top of the beds are another 40 cm high. That's well above my waist and will make picking tomatoes or cucumbers later a bit of a chore. You can probably appreciate the height issue in this picture I posted earlier.
What I'm going to do is cut the legs of my beds down so the beds are 40cm off the ground. I am then going to sink a barrel into the ground near the fish tank and drain the beds into there. I will move my fish tank pump into this sump and use it to pump water into the tank and into the grow beds. The tank will be fitted with an overflow tube that drains into the sump. This system has been tested and featured by Murray Hallam out of Australia. It's called "CHOP", for Constant Height, One Pump. The "constant height" refers to the fish tank water remaining at a constant height, as it overflows into the sump, and no longer raises and falls with the filling and draining of the grow beds.
Yesterday, we cut one of the tables down, put a new grow bed on top, and filled it with new gravel. Unfortunately, the 300 kilos of gravel were not enough to fill the bed, so I could not get it hooked up to the system yet (or transplant my plants to it).
Tomorrow, I'm getting 900 kilos more delivered and will fill the rest of this bed, one more large black bed, and the bath tub. I also plan on getting the barrel sunk and the pump placed in it so the system is fully working in the new configuration. Will post lots of picks with the new set up after it's all done, if I'm still standing!
Almost forgot: One of my fish has delivered dozens (maybe 100?) of fish tadpoles! I knew this would happen eventually, but was very pleased and excited to see it happen. Maybe I won't need to buy any more fish. Will try t get some pics taken, but they are so tiny, I don't know if they'll show up.