HydroCucs 2024

The cucs are doing better than any prior year, but still not convincing me that hydroponics is worth the effort.

HydroCucs 2024

TLDR: The cucs are doing better than any prior year, but still not convincing me that hydroponics is worth the effort.

I've harvested more than a dozen cucumbers so far from my 4 plants which makes this year the most productive yet. The plants have all climbed up at least a meter each and have all produced fruits.

Things that are going well:

  • More cucs than ever before! Wrapping them before storing in the fridge keeps them fresh for a week.
  • My homegrown monitoring / data logging ( now hardwired to power ) is finally providing year-over-year insights ( see below )
  • temperature regulation is better than last year - mostly from the changed design of the system ( RDWC vs NFT ), and using shade cloth all the time.
  • No plants have been lost to root rot (yet) - probably because the roots are now completely submerged in nutrient solution and not just sitting around with swamp crotch.
  • I finally realized I was forgetting to add Calcium Nitrate and Magnesium Sulfate - both of which are considered essential for plant development - this itself could explain a huge reason for my struggles in the past.
  • Citric acid is working great as a dual-purpose additive for lowering the pH of my supply water ( tap water ) and neutralizing some of the bicarbonates that come along with it. Regular tests of pH and alkalinity have been about 6.0 and 160 PPM respectively, on average.

Things not going well:

  • Foliage is still dying off from what looks like interveinal chlorosis, this has continued even after remembering to add the calcium nitrate.
surviving but not thriving

Lets geek on the data

The best thing about graphs is that the more you stare at them, the more they make you think. This is what I'm looking at every day. The big yellow curve is the outdoor air temperature and the red threshold is the temperature (78F) below which I am trying to keep the nutrient.

A few warm-ish days back in May, easily keeping nutrient temp below 78F

By looking back at a comparable stretch of hot days from July of 2023, I think I can say I'm keeping my roots cooler this year. The green line is the water temperature inside the bucket, and the air temperature would have been even hotter. Bleh

2023. swampy inside those buckets!

Then here is the same stretch of days this year, which were even hotter. Notice that the water temperatures are not affected as much by the amplitude of the hot afternoons.

By zooming into the last two days you can see where I put ice-packs in the reservoir as a countermeasure:

The cucumbers are struggling with the heat, but so far the nutrient solution seems alright with no sliminess or smells. We'll see how many more days things can hold up at this temperature. The trouble is that it doesn't cool off at night. In the week-long graph above you can see how the nighttime low temperature is creeping up and the nutrient temperature follows suit.

I probably don't want the nutrient to make this same temperature fluctuation daily - it would be too dramatic for the plants ( I think ). However I notice that the reservoir doesn't cool as quickly as I would have expected. I'm trying to figure out how to take better advantage of the cooler evening when I need to pre-cool for the next day.

why isn't the reservoir cooling off quicker in the evening?

Long term pH management

My citric acid regimen seems to be working. I mixed up a specific concentration in a one gallon jug and then I add 1/2 cup of it to every gallon that goes into the reservoir. I try to do this and let it sit for a few hours before adding any other nutrients. ( This might just be superstition, but I feel like it needs some time to work its magic. )

By taking readings over the past few weeks I can see that I have a stable pH of about 6.0, and the alkalinity is staying under control ( not building up ).

Long term nutrient management

Especially since I've starting using all the components of a balanced nutrient solution, I realize that there is no way to really monitor this balance. I can take TDS or EC readings with a meter and measure alkalinity but I can't actually determine if the plants have been feeding unevenly on a particular component of the solution.

My solution to this is to 'rotate' a few gallons of solution every week or so, meaning that I remove 3-5 gallons ( pouring it on landscape flowers and herbs ), and add back a freshly mixed and balanced 3-5 gallons. Of course this won't re-balance everything, but it will be a step in the right direction, and its less drastic than trying to fully swap the full reservoir.


It's working, but is it easier than dirt? I'm not convinced. If nothing else it is a very abstract way of learning about all the amazing things that dirt is capable of doing. Maybe if I scaled the system up to a lot of plants then I would start to see the returns?

Since I'm trying to declare victory - I might actually give up on this idea next year, or I might decide to try a different crop, or a different hydroponic setup. Sticking with a leafy-green crop would be more straightforward than cucumbers ( which have to completely fruit before being harvested ).

At the end of the season I'll reconsider and see if I want to put in the effort next year.