Hola to All!
Yes, I am in Mexico, the Sonoran desert to be more specific. and it is hot here, of course. And I need some advice on how to proceed (or not!) with my drip bucket system during the (very) hot summer months!
My current outdoor, non-shaded setup is:
- 14 std 5 gal drip buckets with various combinations of 3.75" and 6" net pots in the lids.
- All buckets are wrapped with "Panda film" to block light and reflect some sunlight to reduce heat. Lids covered as well except for net pots.
- 30 gal
nutrient reservoir (Igloo Quick&Cool Camping cooler) with air bubbler and 1,000 liter/hour submersible
pump. I also have a smaller pump in the return line to boost return flow over normal gravity return.
- Plants are mostly tomatoes, with one butternut squash and one cucumber plant as a test of using the same nutrient levels for growth.
- Current feeding cycle is:
Daytime = 20 minutes on every hour
Nighttime = 15 minutes on every hour
- Daytime air temp is now in the 90's during the day, dropping to the 70's at night
The Problem: Nutrient temps
I have tried various Peltier cooling devices, and even converted a mini-fridge to a chiller, running 50' of thin-walled hard plastic 1/2" feed tubing in a bucket of water in the fridge. The fridge simply cannot keep up with the heat load produced by the buckets, reservoir, connecting hoses, etc. I can get only get about a 5 deg C drop in the ambient temp of the
nutrients.
Inside the buckets I have measured up to 104 deg F during the hottest part of the day, which of course is not 'ideal' for any plants! Dropping the nutrient temp down to around 90 deg F is about the best this current setup can do.
Calculations indicate I would need about 18,000 BTU's (1.5 ton a/c) to properly cool the water down to 70 deg F or so. I simply cannot afford that for something I would only use 3-4 months a year.
Temps have been this high for almost a month now, and I am astounded that the tomatoes (cherry, salad, and regular) are still producing great fruit, tho the regular tomatoes are just now starting to ripen. The cherry and salad varieties are producing pretty good at this point.
So my question is: Can I further mod the chiller unit for better efficiency?
So far, I have not removed the ice compartment "box" or moved the thermostat. I have removed all air deflectors, etc. and put in as many water bottles as the unit can hold.
Would it really help to remove the freezer box itself?
Should I move the thermostat into the large bucket with the looped tubing and water?
Even small, incremental improvements in things may help, but I am thinking the plants are going to simply give up soon if I don't make some improvement. And the really hot months of Jul and Aug are yet to hit, LoL.
TIA,
Monty
[Edit] By "thermostat" above, I really meant the 'sensor' for the thermostat!