Hi andyhitomi,
I am in Northern Thailand and working as a consultant on various projects, at this moment in Sri Lanka and Maldives. I'll keep it briefly here as I prefer contacting you in private eventually. Forums can be a great source of information, but some times a following controversial debate can be confusing and frustrating as well.
Firstly, the bug you deal with is most probably a leaf miner larva called Liriomyza brassicae. Description:
Liriomyza brassicae - Serpentine leafminer
And here:
bug guide
It's very commonly spread in S.E.A. If it only affects parts of the plants it's often not treated with insecticides. You can clip or cut off affected leafs or only parts as soon as you spot them. That is what I often do. Tomato plants do not mind if they get a little pruned in such way. It's only a treat for most plants if largely spread - see Wiki description.
To prevent seedlings to get affected early, which isn't a good thing anyway - as the tiny plants may delay development considerably, - you should
cover them with a so called Aphid-net, that prevents miner flies to lay there eggs on them in the first place. That is what we use in Thailand for seedlings and with hydroponics.
The problem is not "water born", and as long as your plants grow well with the combination of the pond water and your
nutrients, - I wouldn't be concerned (or not give priority) to this part.
Again, I am glad to help out and get in touch with you personally. You can always contact me by P.M. at this place from your side. But (and this doesn't actually concern you at all andyhitomi) just saying that I will not engage in any futile debate here anymore that may follow my explanations and advices by certain members who seem to have a strong urge for controversial debates.
This actually happened systematically in the past, and hence I will not reply to any "invitation" of that kind. I am in no mood for that and nor have I got the time.
