Hydroponics in the tropics

[ChrisInTheTropics]

Hi, beginner here, I live in the tropics and have a pair of setups running, sharing a 60L reservoir that is buried to its neck in the ground in the shade. The temperature in the tank is about 26c in the early morning and ranges up to 28c or so through the day (the water in our deep garden well comes out at 23c, cold showers don't exist here !)

From reading up on it, that seems to be ranging from 'a bit too high' to 'way too high' as it is, and that's buried in the shade.

I'm about to set up a new pair of larger units which will be in direct sunlight the middle of the garden, which is paved, so I can't bury the reservoir, so I want to do whatever I can to reduce any ill effects of the high temperature of the nutrient solution.

I could put ice packs in or buy a chiller but one is a daily or even twice-daily faff, the other means more cabling and both will have initial and ongoing costs so ideally I'd prefer to avoid those solutions.

For the first grow in the new units I'm going to start with a big white polystyrene box for the tank, add a shade above and will monitor the temperature and see how it goes.

Might anyone have any tips for hydro in hot countries ? - I could bury the reservoir in the shade like the other one but that would add two pipes across about 8m of garden and a path to the only place I can bury big containers, plus probably another pump to buy and power, which isn't great.

I'll see how things go, maybe the plants/seeds I get here might be more resistant to temperature than ones bought in the west ?

 

[PHunkyFarmer]

Starting with a reflective, light container, like a white styrofoam one, is a good way to keep your water tank cool by shading and insulating it. You should also think about getting more air flowing around the tank and using bigger water amounts. This helps smooth out any big temp changes without needing tricky cooling stuff.

 

[ChrisInTheTropics]

Thanks, I've used a styrofoam box with one of the rigs (and house the mains gubbins in smaller ones), it's a good quick solution; but I suspect the're a bit fragile for long-term use and not ideal to get a tight seal through, also they're just too darn flat to get a good volume of water in.

As you suggest I want to get a larger reservoir (and am moving away from the single very large shared tank buried several metres away idea, too much pipe, too much pumping and too much of a single point of failure/risk of killing everything at a stroke) so I've settled on tall plastic bins with a reflective galvanised steel sheath around them, with a cm or so gap between that and the plastic bin wall.

It helps that I already have a few of the green plastic bins and a roll of the steel from other projects - the bins are much sturdier, easier to work with and to get a good seal through, and can be vigorously cleaned without bits falling off.

The steel surround seems to keep the sun at bay rather well; what doesn't reflect gets absorbed and then convects/radiates away given a bit of air gap between the steel and the bin, temps are noticeably lower than without the steel surround, and also lower than inside the styrofoam box.

I would like the reservoir to be larger than one bin though, so today I'm converting one of the rigs from a single bin to a double, the idea is to share 3 tanks between 2 rigs. One common tank that takes the 2 return feeds and has the UV and air pump in, this is connected by a pair of pipes (one near the bottom, one about 2/3rds from the bottom) between the return bin and the two bins with the pumps that feed the two rigs.

Seems a bit over-complicated but my reasoning is that it means a larger overall reservoir that is common to both rigs (albeit contained in 3 bins), cuts down on the measuring and tuning PH/TDS/EC, shared air pump and UV and so less cabling and power sockets. The 2 'levelling' pipes at different heights help make sure there's no 'dead' water, create some nice turbulence and keep the 3 bins pretty much evenly filled at all times.

I'll keep to just 2 rigs per 'tank assembly' so as to not have too many eggs in one basket and allow me to have different nutrient levels, I plan to have maybe 6 rigs in all. This will halve the number of mains sockets and measurings/tunings I need to do, and give each rig a larger volume of nutrient than with it's own dedicated bin.

 

[dtp]

Your temperature sounds perfect to me.. check this story >> blog best cultivation temperature

 

[ChrisInTheTropics]

Thanks for the link, I'll never get to 25c without a cold-making device of some kind, water comes out of our well around 26c. I'll be happy if I can keep the reservoir below 28 in the middle of the day.