Soft water nutrients are base feeds formulated for water that has little or no calcium and magnesium in it – reverse osmosis, rainwater, or a genuinely soft mains supply. They carry the extra calcium and magnesium built in, so you are not adding it separately and guessing at the ratio.
Which version do you need?
Your water
Formulation
RO or rainwater (near 0 ppm)
Soft water
Soft mains supply (under ~150 ppm)
Soft water
Hard mains supply (over ~200 ppm)
Hard water
Most of London and the south-east, Croydon included, is hard. If you are on unfiltered mains here, the hard water version is almost certainly right – running a soft water feed on hard water stacks calcium on top of calcium and pushes EC up for nothing.
Check before you buy
The number you want is your source water EC or ppm, measured with a meter – not what the water company publishes, which is an average across a region. See pH and EC meters. If your tap reads under about 0.3 EC, buy soft water formulations.
If you are running RO
You are starting from zero, which gives complete control but no buffering – pH will move around more, so check it more often. Some growers deliberately blend RO back with a percentage of tap water for stability. See CalMag if your chosen feed does not include enough.
We are a hydroponics shop in Croydon and we know the local water. Bring us a reading, or tell us your postcode, and we will tell you which formulation you need. Discreet UK and European delivery, and excellent customer reviews on Trustpilot.
