Ballast Question

[lucius]

I have a four bulb TekLite T5HO fixture with two ballasts.  I've been using all four bulbs but I'm wanting to try just three to see if it will help combat my BBA.

Does anyone know if I only run one bulb, will it damage the ballast in any way or shorten it's life span?  I have already confirmed that it will run with just one bulb plugged in.

My other option is to raise the light and keep all four bulbs on.

TIA.

[charlie]

I can`t confirm or deny if it has any long term damage, my guess is no.
I have done it without any visible issues, eventually went back to four bulbs & raised the fixture.
Regards

[lucius]

How high do you have your lights now?  I'm following this graph and it suggests 12".  Mine are on the stands right now and it's six inches above the top.

[exv152]

How tall is your tank, from the rim to the substrate?

[lucius]

This is over my 90 gallon so the tank is 24".  From rim to substrate, it's about 21, 22"

[charlie]

On my 25 gallon - 4x 24 watt Tek - about 6 inches  there is a glass top on that tank
My 79 - 4x54 Tek about 5 inches , open top.
Charts are good reference, but they don`t factor in ambient light, or do they tell you if there par reading are in an empty tank or water filled, type of fixture , bulbs , age of bulb etc.Personally I use them as reference & tweak from there, the plants tell me the rest.
I have no idea what lumens, par or other, the plants know 

[lucius]

Just to close this thread.  I talked with an electrician and he said that the new ballasts are meant to work that way and there are no issues with just running one bulb.

In any case, I went back to four bulbs.