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Newbie question re compact fluorescent watts and ballast

1141 Views 3 Replies 2 Participants Last post by  waterspider

Quick question. When looking a replacing non-integrated compact flourescent bulbs, can you increase the recommended watts at all, or would I need to change the ballast built into the tank hood?

Hoping someone can help me here. I'm in the process of learning about lighting for my first proper planted tank, and have run into a bit of a wall with the tank I was planning to use: aquastart 500 with fittings for 2 pl x 11 watt bulbs (g23 cap) Not only does 22w mean very low lighting on the wpg rule, I'm finding UK suppliers of G23 aquarium bulbs incredibly restrictive. I've not got equipment to measure par, so am really having to rely on manufacturers for spectrum info.

I can get an attachment to use four pin CFLs instead, which gives me more options (up to 36w per bulb - though even 18s would probably give me enough of a boost for a low-tech tank.) I just can't seem to find any info on the aquastart ballast to know if there is any leeway there.

Any advice most welcome. I've been finding the articles and debates on lighting on here massively useful.
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Popping this here on the subject to read properly later ( getting late in the UK!)
Compact fluorescent bulbs, that look like:

are driven at the wattage the ballast is designed to drive them to. Some ballasts will handle more than one wattage, but those require changing how they are connected to the different wattage bulbs. I have put higher wattage bulbs in a light and the bulbs worked, but didn't last very long before the ends blackened. But, I also have changed the wiring, per the manufacturers directions, and used the same ballast successfully.
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Thanks hoppy - as far as I understand that's the same bulb with a different end cap fitting, which is just down to manufacturers preferences.

Could you indulge me while I summarize what I've learned to make sure I'm starting to get it? I'm finding this the toughest subject so far to get my head around!

All flourescent lights need a ballast to "start" and run the bulb, using different power levels to do so. Household CFL bulbs have the ballast built in, these ones have it in the aquarium lighting unit. Ballests can either be magnetic (cheaper, limited watt range) or electronic (runs a wider range of watts)

You can "overdrive" by putting a lower watt bulb in a higher watt ballast, but this reduces bulb life and might be dangerous. You might be able to "underdrive" by putting a higher watt bulb in a lower watt ballast. However, it's likely the ballast range means you won't be able to go up all that much higher than the ballast as it simply won't "start" it, or could flicker. Also, chances are it's not going to make any difference to the output anyway.

So for this unit - which I'm going to guess is magnetic, given that it's a pretty cheap beginner's tank, I "might" be able to run an 18watt bulb in the 11 watt ballast, but never a 36watt.

And if I want flexibility in plant choice I'm going to have to rethink the unit. Darn!

Given all that, would I be right in thinking branded aquarium lights are a bit of a waste of money for very low light/ display? I'm trying GE Biax 11w, 6,5000k, 900 lumen in there at the moment while it cycles to see if they have any adverse effects. (2 for £5 instead of £17 each!)

Final question, do I have to bear ballast in mind with T8s also?

I have a second fluval tank that takes 2 x 20w T8s. I'd planned for the aquastart to be my learning tank, but I'd like to sort out the fluval also.
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