Why Does Ph Fluctuate More In Hydroponics Than In Soil

Written by: Soufian b. Harvey

Hydroponics often requires more pH adjustments than soil, even if both setups seem stable at first. This comes down to several differences between how water and soil systems handle pH changes. So, why does pH fluctuate more in hydroponics?


No Natural Buffers Like Organic Matter

One big reason is that soil naturally has buffers that help keep the pH stable. Things like minerals and organic matter in the soil act like shock absorbers, slowing down how quickly pH changes. In hydroponics, water doesn't have those natural buffers, so any small change in pH can have a bigger impact, and fast.

Root Excretions Affect pH More Rapidly

Another thing is that roots give off substances that can alter pH. In soil, these root excretions get absorbed or broken down more slowly, but in water, they can shift the pH almost immediately. There’s nothing there to slow down the change like there is in soil.

Evaporation Concentrates Nutrients

Evaporation also plays a role. In hydroponics, when water evaporates, it leaves behind concentrated nutrients. This makes it easier for the pH to shift, which doesn’t happen as dramatically in soil since soil has better control over moisture levels.

Root Excretions Accumulate in Water

Root excretions in hydroponics don't have anywhere to go, either. They just build up in the water, messing with the pH until you change it manually. In soil, though, these substances can get flushed out naturally or just absorbed into the ground.

Soil Microbes Help Stabilize pH

Lastly, microbes in soil also help keep pH steady. Bacteria in the soil break down organic material and keep things balanced, but in hydroponics, without that bacterial population, you’re left on your own to manage pH swings.


So, these are the reasons pH tends to swing more wildly in hydroponics. But with regular monitoring and small adjustments, you can keep things running smoothly and avoid the bad stuff.

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