// the grow lab

Know what feeds it

Cheat sheet for pH, nutrients, indoor grow media, and outdoor soil types. Tap a tab below.

pH Scale Decoded

pH measures how acidic (low) or basic/alkaline (high) your water or soil is — on a 0–14 scale, where 7 is neutral. Most living systems have a sweet spot, and missing it means plants stop eating and fish stop breathing right.

0–4

Strong Acid

4–5.5

Acidic

5.5–6.5

Slightly Acidic

6.5–7.5

Neutral Sweet Spot

7.5–8.5

Slightly Basic

8.5–14

Strong Base

battery acid, lemon juice

vinegar, blueberries' happy zone

best for many hydroponic plants

AQUAPONICS GOAL — pH 6.8–7.2

seawater, eggs

ammonia, drain cleaner

Why it matters

pH < 6.5 → plants can't absorb iron, calcium, magnesium → yellow leaves
pH > 7.5 → fish stress, ammonia becomes more toxic, bacteria slow down
Aquaponics target: 6.8–7.2 (a compromise between fish, bacteria, plants)

How to adjust

To LOWER pH: add a few drops of phosphoric acid OR more CO₂
To RAISE pH: add crushed coral, eggshells, or calcium hydroxide (slow + safe)
→NEVER change pH by more than 0.2 / day — fish need time