I was not able to get to the farm until Saturday (I normally go Friday). Tropical Storm Thomas wreaked havoc across Costa Rica, knocking out bridges, roads, water and electricity all over the place. One community suffered a massive landslide that killed over 20 people. In another, 50 homes were destroyed by a wall of mud (fortunately, people had already evacuated).
By Saturday, there was one route open to the farm. The storm had passed and clean-up was underway everywhere. The road was dirty, but passable. Here's a pic of one portion of the road, mostly cleaned up after a small landslide:
(Between Puriscal and San Pablo)
Upon entering the greenhouse, I immediately noticed something was wrong. My bath-tub grow-bed was just fine: the plants had grown some, and despite looking a little pale (due to nutrient block-out caused by high PH), they were upright. In the other grow-bed, the plants were severely wilted - some completely lying down on the gravel.
Other grow bed - major trouble!
What had happened was the siphon failed. It only failed for a few hours, but in this climate, that was enough for the sun to heat up the bed and gravel. The bed and gravel were warm to the touch. The good news is the siphon didn't fail on its own. Carlitos had shut the pressure-release valve that allows some pump water to spray out upon the surface of the tank. Without this valve set correctly, inflow into that bed is too high for the siphon to auto-shut-off.
Also, I noticed the drain pipe from the grow-bed to the fish tank was sagging big-time in one point, essentially making it so water would have to go uphill. The pipe was fine last week, but with the heat and the weight of water going through it for a week, it sagged. I fixed this with some blocks and got the siphon going again.
After just a little more than an hour, the plants had begun to resuscitate, which I found remarkable.
Last week, I wrote about my PH problem. I decided to drive down to the nearest river in order to extract and test some river stones. I put these in a plastic bin filled with water Saturday.
On Sunday, I tested this water and the PH was again high! I couldn't believe it! It wasn't as high as my gravel water, but it was still higher than what the water that was added to the stones was.
Suspecting that this may be due to residual sand left on the rocks, I decided to add a lemon to the mixture. This immediately brought the PH down to 6.0-6.2. Four hours later, and that PH is still holding, so I think whatever caused the PH to rise initially is either not something in the rocks themselves, or if it is, it's not something the rocks will release more of when the PH drops. I brought the bin and PH test portion of my water testing kit back to the city with me and will test throughout the rest of the week.
If the river stones prove useable, I will next have to devise a way to get down to the river with a rock-sifting arrangement and load the truck up.
In other news, the fish look good despite nitrates at between 20-40ppm. PH continues to be through the roof. Quite frankly, I'm impressed with how good the plants look despite the high PH. Ammonia continues to be about 0.25ppm. Carlitos has also been measuring ammonia daily, and it's yet to have gone above 0.25ppm. This could be due to the large size of my fish tank, and small quantity of fish. I'll keep things just as they are until I can replace my gravel.
And here's a better picture of the set-up as it now stands. There will eventually be at least 2 more of the large black grow beds. The fish tank is in the back left corner.