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Maintaining stable pH is one of the biggest challenges hydroponic growers face. One day your nutrient solution is sitting at a comfortable 5.8–6.0, and the next it has drifted sharply into acidic or alkaline territory — sometimes with no obvious explanation.
In today’s blog we break down the real science behind pH instability and explains why some fertilizers cause significant swings while others remain stable.
If you’ve ever found yourself constantly adding pH up or pH down, this is the guide you need.
In hydroponics, nutrients are only available to plants within specific pH ranges. Even a small drift can:
Most growers manually correct pH, but understanding why it drifts is the key to long-term stability.
Gold Leaf (US) and Liquid Gold (UK) are unique one-part, pH-perfect fertilizers that:
But what allows a fertilizer to stay stable when others don’t?
The answer lies in nutrient balance — especially nitrogen forms.
Plants primarily absorb nitrogen in two forms:
Each one has a direct effect on pH when taken up by the plant.
They release hydroxide (OH⁻) back into the solution → pH rises (becomes more alkaline).
They release hydrogen ions (H⁺) → pH falls (becomes more acidic).
Most hydroponic fertilizers are dominated by one form—usually nitrates—which means:
✔ pH looks stable when mixed
✘ BUT once plants start absorbing nutrients, pH rises sharply
✘ Leading to constant correction with pH down
Gold Leaf/Liquid Gold balances these nitrogen forms correctly and adds a unique buffering systems to prevent the swing altogether.
It’s not just nitrogen. Plants absorb positively and negatively charged ions differently:
Potassium (K⁺), Calcium (Ca²⁺), Magnesium (Mg²⁺)
➡ When absorbed → pH drops
Sulfates (SO₄²⁻), Phosphates (H₂PO₄⁻)
➡ When absorbed → pH rises
If your nutrient blend is unbalanced, pH drift becomes unavoidable.
Plants naturally release organic acids to help access nutrients when they feel deprived.
These include:
If your plant is deficient in phosphorus, iron, manganese, or other micronutrients, it may acidify the solution in an attempt to free them—causing unexpected pH drops.
Microbes in your system—especially nitrifying bacteria—can convert:
Ammonium → Nitrate, releasing hydrogen ions (H⁺)
➡ This acidifies the solution
This is one reason deep water culture (DWC) or systems with biofilms often experience pH drifting downward.
Similarly, microbes breaking down sugary additives (molasses, carbohydrate boosters, bud enhancers) can create acids through fermentation.
This can cause rapid pH drops in warm, oxygen-rich environments.
➡ Raises pH
➡ Makes pH harder to bring down
➡ Increases buffering capacity
➡ Very little buffering
➡ pH changes quickly in either direction
Plant and algae uptake of CO₂ can create minor pH drops, though this is much less dramatic compared to nitrogen-driven changes.
Different crops prefer different nitrogen forms. This means:
This variability is why crop-specific expertise becomes a competitive advantage — a “knowledge moat,”.
If you’re constantly adding pH up or pH down, or you’re seeing wild daily swings, it’s a sign that:
Eutrema can help diagnose these issues and recommend practical solutions.
pH drift is normal — but extreme swings are not.
By understanding how plants, nutrients, microbes, and water chemistry interact, you can take control of your hydroponic system and avoid endless corrections.
Using a balanced, buffered, pH-perfect fertilizer like Liquid Gold eliminates most pH instability and gives growers a massive advantage in consistency, yield, and long-term reliability.
If you enjoyed this deep dive into pH science, make sure to follow Hydroponics Daily, leave an Apple Podcast review, and explore the innovative technologies at Eutrema.co.uk.
Article by Dr Russell Sharp
If you would like to keep up to date with subjects just like this, you can listen to both our podcasts! Links can be found bellow:
Hydroponics Daily Podcast: https://podcasts.apple.com/us/podcast/hydroponics-daily/id1788172771
Cereal Killers Podcast: https://podcasts.apple.com/us/podcast/cereal-killers/id1695783663