I have found that any filters placed in the lines accumulate slimy deposits and plug up. Keep float clear of pump and lines. Green algae will quickly grow on any surface which light can reach which is why the buckets are gray and the hoses are black. It is difficult to grow perfect tomatoes. The bucket system does not have the weight to keep them from falling over so the tall vines must be supported from above.
Cucumbers are productive and easy to grow.
Lettuce and basil are easy to grow. General Hydroponics MaxiBloom and MaxiGro are the most general purpose and easiest. The FloraBloom, FloraGro and FloraMicro system is for more advanced use. You will also need a pH adjustment kit. I believe this system has the supply and drain flow to be expanded to 20 and perhaps 30 buckets by simply screwing in an additional 10' drain and supply line to the end.