wilma recycling used water

oight to all the growers in the know.
im having some trouble im growing with a wilma 10 pot planter and yes i have looked for aswers on google before i came here anyway,what i dont understand is the tray with the pots on does this tray go on top of the water tank becouse im very aware of the ph in the water and if this method is used wont this contaminate the water in the tank below becouse it will be recycling it? also what timing should i have the pump to turn on to pump water and nutriant solution through the system or should it be pumping water 24/7?i have widow cross ice for my first grow with this system also doing 10 in soil ill post my pics when i get some info on starting this wilma system

your all part of a unjust system soon the babylon will fall

if i remember correctly the wilma is a flood and drain system that ranges from 4 pot to 20 pot the flood and drain timing can differ with prefrence 10 minflood 20min drain works for a friend in flood and drain and ph can be very irregular in flood and drain anyway.be safe the postman