Dimmable ballast?

[The Saltman]

Hi guys,

I see some ballasts have the option to purchase a dimmer for them. I was wondering if this is worth it and what is it used for?

[The Saltman]

bump

[JRaquatics]

The dimmable ballast usually overdirve a bulb at its highest setting. It allows you to aclimate corals to your lighting easier. You don't have to use screens or multi placements. I think it is handy. I use an adjustable electronic coralvue ballast.

[The Saltman]

Does it just overdrive a bulb or will it underpower them as well?

[BeanAnimal]

JR that is not correct. The highest setting is simply the ballast operating without dimming. Any setting below that decreases the output.

In any case What type of bulbs? MH, T5, VHO?

There are different types of dimming ballasts. Commercial T5 dimmables are usually controlled via a 0-10V signal (dimmer).

IceCap ballasts use a proprietary variation of 0-10V and many MH dimmables use a proprietary controller as well.

[The Saltman]

http://www.reefexotics.com/lumen_bright_retro.htm

Here is the link to the kit I am looking at. You will see at the bottom of the page the option to purchase an upgrade to dimmable ballast. I am not sure what it is and if its worth it.

[BeanAnimal]

I think I read someplace that the dimmable coralvue had a significantly lower output than the non dimmable ballast. It is a not a bad feature but it does not appear controllable from an outside controller. So you will not be able to simulate dawn/dusk or whatever. Sort of pointless other than if you change bulbs and need to acclimate... still sort of pointless.

[Roland Jacques]

this may be a dumb question but When these MH ballast are dimming do they use less current? i guess i would like to no are they efficient

[Roland Jacques]

Bean,
I was thinking they may have a good application for people who want to get the most out of their lamp life.
since you loose 20% of PAR during the first 4 months then 10% more over the next two years. Maybe then buy your lamps accordingly and ramp them up at the same rate they decline. Use the same lamps for a very long time.

[JRaquatics]

<a href=showthread.php?s=&postid=11311183#post11311183 target=_blank>Originally posted</a> by BeanAnimal
JR that is not correct. The highest setting is simply the ballast operating without dimming. Any setting below that decreases the output.

In any case What type of bulbs? MH, T5, VHO?

There are different types of dimming ballasts. Commercial T5 dimmables are usually controlled via a 0-10V signal (dimmer).

IceCap ballasts use a proprietary variation of 0-10V and many MH dimmables use a proprietary controller as well.

When I contacted coralvue with some questions they stated that if I turned the dial all the way up I was overdriving the bulb. This is true since I just had it tested with a par meter this weekend. 7/8 of the way on a coralvue ballast is optimal an any higher it is overdiving the bulb and giving lower par ratings.

I was also told that by dimming the ballast I was not going to be saving any wattage.

[BeanAnimal]

I would not call that overdriving then (at least in the sense that the term is used in this hobby). We overdrive to increase output. If you turn the knob past the optimum setting and it decreases output, then it is pointless.

Anyway, this is not how a typical dimming ballast would work.