A three gal container is way too small for Big Beef, 5 gal is pushing it. Personally, I wouldn't use less than a 15 gal container for that particular variety. Big Beef plants get enormous.

Water plants in morning, not evening, so that foliage and soil surfaces have time to dry out. No need to add sand to potting mix -- actually I'd advise against it. If anything, it will hinder drainage, not help it. Same with the rocks/sand in the bottom of the pot (a common misconception). Plenty of information in the container gardening forum on how to build good container mixes.

Right now I'm using a fertilizer that's 30-10-10

Way, way too much nitrogen, especially considering you've already added bat guano and other fertilizers to your potting mix. Also, if your plants are only two weeks old (do you mean from seed or from transplant?) they need little, if any nitrogen at this point.

Orthocide (captan) is not really as effective as a fungicide for fungal foliage diseases of tomatoes as Daconil (chlorothalonil) is. As far as continuing to use it as a soil drench past the seedling stage for this soil mold, what do the directions say? Because that's what I'd recommend what you'd follow. I don't think continuing to use it past a seedling or cutting stage as a drench is a labeled use, and you'd also want to research and then consider toxicity.

Penncozeb? Works by coating/sealing leaf surfaces, so using it as a soil drench isn't going to be helpful. Also probably shouldn't be mixed with the captan like you're doing (I don't know, but would suggest you check). Again, my concern with using it as you are doing (not a labeled use) is toxicity to you.

Did you throughly read the instructions for both of these products before you used them? This is so VERY, VERY important to do.

I think the solution to many of your problems is going to be figuring out how you can somehow provide a drier environment for the plants, whether it be growing in a raised tunnel, a greenhouse, etc. Or perhaps even some sort of makeshift structure you rig together. Having rains every other day as a regular feature of a growing season is just not going to be optimal for tomato plants.

There have been a number of posts on the main tomato forum discussing the challenges of growing in hot/rainy/humid climates that you might find helpful.

Here is a link that might be useful: tomato forum

It occurred to me that you had mentioned watering two week old plants (seedlings?) every single day. Is that correct?

If so, that would probably be too much water, and could be contributing to the green mold.

Another thing that occurred to me is the amounts you're using on the captan and penncozeb are really trace amounts (1/16 t for 4 cups of water).

Thanks for your response

I'll keep all of it in consideration next time I do planting but right now it's too late.

I live in Thailand so when I bought the funguscide the man I bought it from didn't speak English and all the instructions on the bag are in Thai. So that's why I'm not following the instructions and I am using only trace amounts. I'll try to find the instructions online somewhere. When I get a chance I'll go back to the shop and try to find some Daconil. I guess I'll have to get the instructions online for that also. I did make a small green house out of 2 clear plastic containers with a glass top and the sides cut out. I put some wire screen along the side to keep the pests out. I only had enough money to do it with one of the plants because those plastic tubs are quite expensive. The plant inside there seems to love it though(see pic). It does help with the rain but not with the humidity. The tomatoes I started myself from Big Beefs I bought at the grocery store so they are 2 weeks old from seedlings.

Hopefully, you'll be able to get the Daconil. Maybe you could buy it online if the shop doesn't have it? See below for instructions for the 29.6% formulation of Daconil (chlorothalonil). In short, it's one tablespoon per gallon of water. Spray all surfaces of the plants once a week or so; it works by sealing fungal attachment sites on the leaves.

As for the green mold on the soil, I think I'd try some hydrogen peroxide instead of what you're using now. Mix the 3% strength about 1:12 to 1:20 and spray the soil surface. You could even water the plants with it; won't hurt them. Numerous posts on GW on using hydrogen peroxide in gardening applications. And of course, trying to keep the soil drier will help a lot.

Here is a link that might be useful: instructions for Garden Disease Control (pdf file)

Thanks a lot for all your advice. You're a star.

Cheers