ok i have a home made water culture system (7 US qts) and i'm having problem with some whitish grayish mold growing all over my growing medium while i just started seedling stage and burried the seeds not even 2 days ago... I needed to know what are my choices fighting this thing back without damaging the plants...

I have added some algae control drops to the water and i have also added a fan which blows over the garden in order to increase air circulation...

other than these 2 what else can i do cuz it does not look like the situation is gettin any better!

if there are any product recommendations plz advise me of exact item brand and/or name/model and plz advise me of where to shop for it (im a newbie and hydro stuff seem a lil hard to find for me when shoppong offline!)

i have 2 other questions which maybe/maybe not related to the main question...

1.can i use orchid soil as growing medium for hydroponic system? (i could not find perlite or rockwool at the local home depot plz advise of location to find it in)

and

2. how important is the light system for a hydroponic water culture garden? i searched out for some light systems and they were kinda expensive and i cant afford them at this time...

would it be enough light for the plants to be located by a window without being directly in sunlight but being supported with 3 sheets covered with aluminium foil behind and around them...

if its is strongly advised for me to have a grow light system (required) can i just purchase an MH or HPS light and a mogul base converter and use a regular light output ...without any reflectors or enclosures... or ballasts?

i maybe able to reverse engeener a reflector and i'm able to spend 30 bucks or so for just an MH light but i wanted to know if the ballast sold in factory made systems is required for one grow light below 200w?

any solution to DIY or cheap grow lights? (below $50 including the lamp)

thx in advance