r/Hydroponics

Got into hydroponics a while back thinking it’d be simpler than soil gardening. It’s not — it’s just different, and the mistakes hit faster because there’s no soil buffering your errors. Sharing what tripped me up in case it saves someone else the trial and error.

1. Ignoring pH drift

I assumed once I set my nutrient solution’s pH, it would stay put. It doesn’t — plant uptake and temperature shift it within days. Lost my first batch of lettuce to nutrient lockout before I realized I needed to check pH every 2-3 days, not weekly.

2. Skipping the EC/PPM meter

Tried to eyeball nutrient concentration early on to save money. Ended up either starving or burning my plants. A decent meter is maybe $20-30 and pays for itself in the first grow cycle.

3. Using one nutrient mix for everything

Leafy greens, fruiting plants, and herbs all want different N-P-K ratios and different strengths at different growth stages. A one-size-fits-all mix works “okay” but you’re leaving a lot of yield on the table.

4. Underestimating root oxygenation

In soil, roots get air naturally through gaps in the substrate. In hydro, if your solution isn’t oxygenated (air stone, proper flow, whatever your system needs), roots suffocate — and it looks like a nutrient problem at first, which sent me down the wrong troubleshooting path for a week.

5. Wrong light distance and duration

Either burned seedlings by putting lights too close, or got leggy weak growth from having them too far / not enough hours. Every crop and every light has different specs — worth checking rather than assuming.

6. Not planning for algae growth

Any light hitting your reservoir or tubing = algae, eventually. Learned this the hard way when it started clogging my system. Blocking light from your reservoir from day one saves a lot of cleaning later.

Wrote all of this (and a lot more) into a full guide — indoor, outdoor, and greenhouse setups included. It’s free on Kindle for the next few days if it’s useful to anyone: https://www.amazon.com/dp/B0HFG5X4BM

What about you — what’s the mistake that taught you the most (the hard way)? Curious what other people have run into.

Is lettuce supposed to grow tall-ish like this? Did I transfer them to the tower too soon (i did when they had 4 true leaves)? Or is just the weather (indoor temp reached 30 the past 2 weeks)?

I have lettuce growing in a Spider Farmer system with the larger ones now at 3 weeks growth. I'm worried that there is crowding happening at this point but that each isn't quite the right size to harvest for a lunch sized salad.

Would it be dumb or smart to fill the blue tub with water and use the same food solution and transport the 3 larger ones there to float?

Window provides good sunlight during the day.

Would not get any water movement... Figured could do this for another week or two to let salad reach peak size before eating.

I put it ca 1,5-2cm deep. The seed had a ca. 1,5cm long sprout. Now i‘m afraid that i put it too deep and it won’t come through. The granulate isn’t too big, i put my hand in the pic for reference. Does anybody have experience with this? Did a make a mistake?

Last winter I ran a Deep Water Culture set-up but I had to deal with water temps rising. I want to try something different using what is it... drain to waste*?* I had really good sucsess with DWC besides the temp issue.

Wanted to grow a couple to maturity before stagger planting and cutting and coming again. Gonna give 2 of them away and use 4 cups of the Lola Rosa for grilled chicken salad tonight!

My nutrients and pH are good and I test them every 2 days. The lights are 12 hours daily, the seed germinate fine. How ci.e I'm not getting little ball lettuce, strings with leafs

Its not much but I just upgraded my setup by created this water station to mix 20+ gallons of solution then dispense via 1/2 hose to the buckets in the tent. I have a 4x4 gorilla tent with a vivosun dwc bucket system. Growing sugar rush peach and lemon drop peppers. I have a little submersible pump. I pump out the old water and dispense new solution straight to all 4 buckets.

I'm looking building a vertical NFT system, with PVC tubes, for strawberries. I could either plug in a water feed into each of the tubes or leave gravity do the work for me a feed the top one then interconnect each level with a slope. It's simpler from a plumbing aspect. Any reason why I should go with the one tube/one feed approach?

I have a larger than average NFT hydroponics setup and I wanted to share some info about various water chillers I have used.

I have 3 NFT systems in 2 greenhouses in a very hot climate. Today was 108F outside and just under 90 in the greenhouses. I try to keep my water temps below 75F but preferably under 70F

My largest system is about 800 feet of gutters, I've used 4 different water chillers.

First chiller was a 1/3 HP chiller from Amazon. It cost about $450 USD and was pretty much worthless. It wouldn't even run when air temps were over 90F

I moved on to Vevor 1.5HP chillers. The Vevor chillers could keep the water below 75F about 75% of the time. During the hottest parts of the day the temps would sometimes hit about 80F These chillers would pull about 1000 to 1200 watts, depending on the ambient air temps. At the time I paid about $850 USD for them.

I tried a 18000 BTU pool heater that could also chill the water. Chilling BTU is not listed but probably no more than half the heating BTU. On its own it was almost as good as the Vevor and pulled about 900 watts. When ran in parallel with the Vevor chiller it was about to keep the water around 73F during the time when the water would have been 80F with just the Vevor. I paid about $540 USD. I wasn't expecting it to do as well as it did for the price. I mainly wanted it for heating the water during winter.

Encouraged by the results of the small pool heater, I bought a larger Aquastrong pool heater/chiller. On its own it is able to keep my largest system under 74F all day long. It is a inverter heat pump and the wattage varies. During the hottest part of the day it pulls about 750 watts and goes as low as 350 watts as it gets cooler. I paid $1039 USD for it.

A couple of things to keep in mind for the pool heaters/chillers is that you make sure it pick one that is rated for "salt water pools" These units will have titanium heat ex-changers that will not corrode. Also both of the ones I tried have a water flow switch and need a MUCH higher water flow rate or they wont turn on.

TLDR Pool heaters / chillers work great with hydroponics.

Harvested my carrots from my second run in 2026. If i can turn around my system quickly i may be able to get one more trial this year.

For Trial 02,
63-days from sowing the seeds, about 55-days from seeing the first green shoots. I believe the varieties i have are between 50-60 days to maturity. I imagine they would still get bigger if i let them go a little longer.

I started with 35 seeds and have about 12-15 that survived. I seem to have an issue early in the growth stage where a lot of the plants wilted and i could not get them to come back.

I did lower the cal nitrate in this batch to try to cut down on the excessive top growth i had in the past and that seems to have worked.

I would say the taste is still great so happy with what i got. Now the kids have eaten them all in one sitting. Need to expand my system if i want a continuous supply. I would likely have to use 3-4 totes succession planted.

The biggest carrot is just bigger than my thumb and about 6+ inches long.

I didn’t realize air tank was clogged so it was not providing oxygen in tank for about 4-5 days. And PH level was a little too high I was able to lower it from 7.56 to 5.78. Will they make it? If yes how long for them to recover? Basil was growing perfectly until this morning when I noticed issues near end of leaves.