What do the directions say?

Doesn't

Generally water soluble fert is measured as 1 tablespoon dissolved in 1 gallon of water to be applied about every 3rd watering or about once per week . Does you fert have a brand name? Is it a blend specifically formulated for tomato plants? That 38% K seems a bit on the high side.

" Doesn't "

Manufactured fertilizers do not come without directions. It is illegal to sell them without. If you did not save the original packaging (something you always want to do), go online and find a label for that product.

I would also be skeptical of a fertilizer with that NPK ratio. Nothing needs K in that high a concentration and even the P is elevated unnecessarily. Ideally you want something approximating a 3-1-2 ratio - that services the widest variety of plants throughout their entire lifecycle. I'd very likely increase that dilution rate further to limit the dosing of both P & K.

4-18-38 Greenway Biotech tomato fertilizer

Here's a link to it on their website with application rates.

And yes, it's in the hydroponics section.

https://www.greenwaybiotech.com/collections/fertilizers/products/tomato-fertilizer

I'm curious why it would be at half strength for plants in soil. You'd think that hydroponic roots in pure water with the fert constantly flowing through would be in close constant contact and able to take up more of the fert than when the same concentration of fert is watered onto the soil maybe once or twice a week, depending on how old and rootbound the pot plant is, and assuming you have regular, perhaps daily watering with plain water as well which would dilute and flush out some of the fert applications. I have no personal experience, so just thinking.

I agree