Going from 175w to 250w. Now what?

[Syris]

I have had 175w MH over my 75g tank for 4 months now. But since then I have changed my mind and I am going to 250w MH.
I just recieved my new lights today, 2 - Icecap 250w HQI MH ballast and 2 - 250w AB moguls (btw great price at oceanencounters) I will be re-using my sockets and reflector. I run my current 175w for 8hrs/day. This weekend I am settting up the 250w.

How much would you decrease the amount of time the lights are on for? And how often would you increase this to get back to a 8hrs/day schedule?


FYI-next week I will be posting the Dual PFO 175w ballast and 2 - 175w 10k Ushio (used, 4 months on them) for sale.

[Scuba_Dave]

Did you buy AB bulbs w/ setup? Trying to org a grp buy if enough people interested - need to order a spare? The 175w are HQI setup?

[Syris]

Yeah I bought the 250w AB with the ballasts as a special sale package. I saw your thread on th grp buy. I may jump in for a spare, still deciding. I haven't seen 250w AB 10k in real life before not sure if I am going to like or not yet.

My existing dual 175w PFO is probe start ballast (ANSI M57) even though I do use 175w 10k Ushios on it (recomended is pulse start M137) but I never had a prob in the 4 months I had them.

[Syris]

So any suggestions on how much I should reduce lights hours when I put the new ones on?

[Scuba_Dave]

You are basically increasing lighting by not quite 50%, so maybe a 40% decrease in lighting would be OK to start. so maybe 5 hrs, then increase gradually to 8 hrs again.'

8 x .4 = 3.2 hrs less

make sense? anyone else?

175
87
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262watts

[Syris]

Thanks Scuba. I got new lights on today and reduced lights by 3hrs. I'll keep an eye on corals for any bleaching and lower light period more if I see any.


As for the ABs I don't see any diff yet from the Ushio bulbs. Maybe when they burn in they will be better?

Later