There is no one best growing medium for hydroponics. If you looking for the answer to what is the best growing medium, you just won’t find it.
The most important thing is to find a medium that works for you. This means you will have to do some trial and error planting – that’s just the way it is.
Of course, you can always get a step in the right direction. Speak to other growers, especially those close to you, and those with the same crop. Speak to your seed/seedling suppliers and see what they say. But in the end, it is your decision, and others really are only offering an opinion.
The YouTube video below, gives a great overview of what medium is on the market and at least one opinion
Here are some things to consider when choosing where to start:
What kind of hydroponic system are you using? There are six basic variants and many sub-variants. (Drip System, Ebb & Flow, N.F.T., Water Culture, Aeroponics, and Wick). Different mediums have different characteristics. Cocopeat has excellent water retention properties but this is not a key requirement for Ebb&Flow designs.
What crops are you growing? Small veggies like lettuce or micro veggies have a very different requirement to plants like tomato and peppers. My general opinion is that the smaller the plant, the smaller the individual parts of the aggregate should be. For instance a lettuce or spinach would not do well in a bed of large LECA balls.
Are you going the aquaculture root? Mediums like perlite have a high ‘dust’ content which would not be good for the fish.
Do you want a consumable medium, or a reuse-able one? Coco peat is difficult to separate from plant you remove and hence needs replenishing each crop. It also has a limited life in terms of number of crops. LECA on the other hand is very effective as a more permanent media.
Can you secure a regular supply and consistent quality of your chosen medium? This is very important in South Africa. Exchange rate volatility and adversely effect your business model.
Do you have the time and space to make up your own mix?
How flexible do you need your set-up to be?