What could be the cause of BER considering the cercumstances listed below

[Lawrence Croeser]

Good day,


What could be the cause of blossom end rot, in my particular case?

I have the following system and conditions:

I live on the East Coast of South Africa.
Our summers are hot and humid. (Summer has stared here)
My hydroponics system is top feed and drain.
I have 4 varieties of indeterminate tomato plants.
My reservoir is 100l, placed in the ground.
My system is outdoors and exposed to the elements.
I use hydroton as a medium.
I feed my plant 8 times per day for 10min per feed.
My nutrients are the typical A + B nutrient from a commercial supplier.
I have lately been adding MPK.
My plants look healthy and grow vigoursly.
The plant types are, a big paste, hillbilly, giant Belgium and carbon.
I have been feeding quite aggressively.
While feed the plant I check the EC in the nutrient tank and the EC as the system drains. I adjust the EC’s to bring these values close to one another. This is in the region of EC 3.
I check my ph regularly and adjust it between 5.6-6.3
The plants are not shaded.
I have started adding a cup of diluted (1ml / l of water fulvic and humic acid twice a week after the last feed, per plant
Two of the four types are more prone to BER i.e. the paste and the carbon.
The plants are well supported and strung.

I have read up a little on BER, but I am not sure what is causing the BER.
I have upped my B nutrient a little (B has the calcium).

I am keen to hear your input.

Many thanks.........