Mh bulb

[mark peacock]

i have just bought a new 400 watt 20,000k bulb for my reef and have change it 2 days ago noticed some corals have not come out i.e. polyps could it be because i went from a 400 watt 10,000k bulb to the 20,000k have i upset the corals:|

 

[Krish]

The PAR rating probably changed significantly depending on the brand of bulbs you used going from a 10K to 20K which may attribute to the polyps not coming out as yet. Just thinking out loud though

 

[mfinn]

How old was the old bulb?
You may just need a break-in period with the new bulb.

 

[mark peacock]

bulb

I upgraded from t5s and t8s bulbs to 400 watt MH about 4 months ago same wattage but only 10,000k but wanted a more blue colour so went to 20,000k 2 days ago.

 

[millepora]

What brands did you switch from and to? Because, some 20k brands are more intense than 10k brands.

So you are saying the bulb was only 4 months old, before you switched it?