I have one of these running on my 3ft...150watts MH...just wondering how come my clam doesnt open up as much these days. I used to have the 10,000K bulbs, but i decided to change to the 20,oook.

Do you guys have any idea of what seems to be the problem?
Regards
Mango :hug:

The difference in PAR in the 20K vs 10K is quiet a bit! The 20K will usually give you nicer color but very slow growth due to a lack of intensity. The 10K on the other hand has about double the intensity, will give far better growth. You have essentially took your clam out of great light and put it in less light so to speak. Most reefers get around this when switching to 20K lights by stepping up a size in wattage. Ie...if they were using a 10K 175 watt light and want the 20K look then they will go up to a 250 watt fixture to regain back some of the lost intensity in switching to the newer "cooler" bulb.

I am of course assuming that your using a 150 watt bulb and switched from a 10K DE to a 150 watt 20K DE. Im assuming too that said clam is directly under the halide light. If not consider movering to a location under the light. A single halide fixture is a bit lacking on a 3ft tank. It is workable but generally you will use a halide for every 24 inches of Tank length. Adding an additional light or stepping up from a 150 watt fixture to a 250 might be better if you are keeping a Crocea or Maxima Clam. Just some potential options to think about...

HTH's!

Thanks. It really helped alot. Thinking of upgrade the tank to a 4X2X2, what lighting would you recommend for it?

Well Im not into the "Blue look" as nice and as soothing of an appearance as it creates, so my preferances will more than likely differ from your personal taste. But dont get me wrong I hate the yellowish cast of light that 6500K's produce too.

My personal recomendations would be 2 x 250 watt XM 10K SE's backed up by at least 2 x 110 watt VHO actinics all powered by ARO ballast as a minimum. Another option that is effcient would be same set up using XM 10K DE's and backed by 4 110 watt VHO actinics. The DE's produce a bit more intensity than the SE bulbs of equivalent wattage and there for the latter recomendation would be close to what 400 watt SE's would produce with out the ridiculas electrcity consumption and additional heat that may have to be delt with. The first combo would handle just about anything under the sun coral, and clam wise. If your a SPS coral or Clam Junkie like myself...then the second combo should carry a bit more weight in your considerations. Both will give your critters good color and exceptional growth if the water quality is suitable. The PAR on the XM 10K series bulb is far superior to any other 10K on the market and is just a hair less that that of the 6500K's! It will produce a arc welder white light with a slight hint of blue.

Just keep in mind that considering the depth that your new 120 gallon tank will have the 250 watt halides should be the minimum wattage. At 24 inches in depth...thats a lot of water for the light from 175 or 150 watt halides to cut through. If the tank is mainly softies and Derasa, Squamosa, Gigas or H. Hippopus clams then the 150-175 watters might be an option. With Maximas or Croceas its 250's all the way or better.

If you are truely hung up on the "Blue Look" you might want to seriously consider 400 watt SE or DE's stoked with the 20K bulb of your choice. I would just use 4 x 110 watt VHO day lamps. Unfortunately bulb choices are considerably limited as far as brands and color temps go and they are of course about 15-20% more costly.

I very much prefer the VHO's to PC and dont have a lot of experience with the T-5's to go out on a limb and recommend them. The VHO actinics in my opinion are far superior to PC actinics although either are workable. Should you choose to use VHO's get the 46.5 inch 110 watt bulbs as opposed to the 48 inche 110 watt bulbs which may cuase clearence problems in the typical canopy. Just a suggestion...

Well you asked for it and there it is. Look at the suggestions provided, do some research to make sure you get what YOU WANT, after all its your fun dollars and your veiwing pleasure that must be satisfied, not mine. I would even go so far as to suggest that you go look at tanks with the kinds of lighting combos that you are considering prior to purchase as lighting at this level is quiet pricey and a mistake here could be a costly one!!! Like I often times say...ask 20 people what the best light set up for a tank is and I promise you will get 21 different answers and a debate thats a real "blood bath". Look long and choose carefully.

HTH's

Cheers, thanks mate :hug:

Your welcomed!

I have played around with lots of different lighting set ups so I have kinda gotten a feel for what works and what doesnt before I finally settled down on the combo I like that seems to give my animals what they like best and still keep my eye pretty satisfied.

I had some really high hopes for XM's new 15K bulb but the PAR is almost as weak as it is on the 20K and I dont want to step up to 400 watts from 250's so...in fact from a visual stand point there was hardly anydifference in the XM 15K and 20K.

BTW, what sorta clam do you have and what size is it if you dont mind me asking?