Dosing boric acid

Hi all,
I have a 63G well planted tank and I'm experiencing some deformation with the new growth leafs. My parameters are kh 6, gh 12, ph 7, light 144W, pressurized Co2. I am fertilizing with Aquamedic Ferreal and Floreal. Because gh is high I doubt there is a problem with calcium, so I focused on boron that could block calcium uptake.
I bought some boric acid that is a powder and my chemistry problem is how much to dose to obtain for example 1 ppm concentration.

Thanks

No, I don't have an ingredient list and I don't know the calcium level.
Could it be a bad ratio Ca:Mg which same effects?
From what concentration up Boron becomes toxic?
As calculation, please correct me if I am wrong:

I put 1g of H3BO3(1000mg) into 1 liter water. This would give me 1000ppm concentration in this 1000 ml solution. So 1ml of this solution would result in 1ppm concentration in 1 liter of aquarium water. Does it mean that 200ml of this solution would result in the same 1ppm concentration for 200l of aquarium water?