New bulbs = cyano?

[kstallbe]

I just put new bulbs in about a week ago. Seems my old MH bulbs weren't really working for about they year I had them anyway, because I had the wrong ballast type. Duh. Live and learn.

So, the new bulbs, 175w 15k Iwasaki, are putting out way more PAR. I've got a touch of hair algae, nothing troublesome. pH is definitely swinging more now. Nitrates are 10ppm or less (API). Phosphates 0 (API).

The thing that's bugging me is the cyano though. Its popping up in lots of difft spots, but not everywhere. Is this typical with new bulbs? Should I raise my lights more up off the tank? They are about 12" away as measured from water surface to the bulb.

Thanks

Keith

 

[kstallbe]

Anybody? What's the usual deal when y'all put new metal halides in? Does your tank go through crazy changes?

 

[Laddy]

Sometimes, depending on how old the bulbs which were replaced.

Reduce your photoperiod, and aclimate your tank.

 

[kstallbe]

Thanks Laddy. I already went from 12 to 8hrs. I have some screening I can add too....

 

[grimreefer01]

when changing lights, especially when the par is way different, it is a good idea to "acclimate" them to the tank, or rather acclimate the tank to the lights is more like it..

this can be done by placing 5 layers of window screen (not the metal or aluminum obviously) over top of some eggcrate that is placed on top of the tank.. Every other day, pull a layer off.. The tank will slowly get used to the new lighting this way, and you wont "shock" the tank nearly as much..