Hi Mike Nelson here.

I use a pair of 400's on my rack and a third 400 which is a switchable ballast in the middle between the two dual filaments. I have to change the bulb on the middle one of course when going from grow to flower. I would have preferred to have three switchable ballasts but I bought the two hps ballasts before I really knew what I wanted. I could have bought conversion bulbs to plug a MH into HPS ballasts but they were expensive.

How do they work for me on my pot crop. Very well actually I expected that the middle with the switchable ballast and changable bulbs would have outperformed the ends with the dual filament bulbs but not the case. They are about the same.

I do switch on 1200 watts of radial florescents at budding time and maybe that is a factor. In the green groth state when the flors are not on, only the dual filaments and the MH in the middle the green groth state is almost the same or the same. I have a pulley lowering system I crank up and down with a boat trailer winch and I keep the 400's 14" over the top of the plants. My grow space is 4' by 8'.I hope this helps you out Mike.

A friend of mine has suggested that I should use one of those motorised tracker and move to two 600 w switchable ballasts instead of what I am using like he does but he is a hydro guy and I am an organic soil operation. I think he outproduces me by quite a bit. Maybe I will just keep my rack and switch to hydro in the near future. Power failures are still scaring me and probably won't do it until I can convert my grow area to a back up generator.

Nelson

Nelson,

Not a switchable ballast, I have one. This is a specialized bulb that is both MH and HPS.

If your ballast is an S51 type, you can use conversion bulbs in it.

Tomatoes do not rely on a photoperiod to bloom so apparently there is no real need to switch bulbs for blooming. I hope this is true, as the HPS bulb encourages leggy plants, at least tomatoes and basil. I don't have a high ceiling where I want to grow the plants so keeping them shorter has a huge advantage, especially if they will produce as much fruit.

Mike