MH bulb change

[Tomoko Schum]

Hi y'all,

Since I did not get around to buy a Lux meter, I did the calculation based on this month's RK mag article on Phoenix bulbs and the equation (of the inverse square law) that Dr. Sanjay Joshi mentioned in one of his article and installed my new light MH bulbs at approximately 1 inch higher position than the old ones used to be. Luckily I have a Oceanlight (Aqua Medic) pendant light fixture that I can move up and down. I think my light level from the new bulbs are matched fairly closely to that of my old bulbs since none of my corals seems to be showing the sign of bleaching after a few days, although the tips of my yellow acro is getting much bluer suddenly (could be the bag of GFO I just exchanged.)
My old bulbs were 1 year and 4 months old. Since I have been bringing down the light fixture over the last 6 month (down to 7 to 8 inches from the water surface), I did not see any color changes in any of my SPS's. Finally at the beginning of April, I started noticing that the faces of my blue zoanthids and bright green zoanthids at the bottom of my tank getting really large, indicating that they are wanting more light. The green color never dulled (while blues turned a bit greyish), though. I plan to bring my fixture down a touch in a week or so so that the faces of my zoanthids will go back to the normal size.

I am really surprised that I needed to raise my bulbs only one inch to match the light levels. I assumed that the light level of my old bulbs were about 75% of the new ones based on data in the RK article. I suppose I could have gone the other way and brought down the light fixture further, but I was afraid of the temp increase this may cause in the summer time (I don't have a chiller.) If I have changed my bulbs last time in the begging of the winter instead of January, I might have been able to lower my light fixture just one more time to extend the usage duration of the MH bulbs further since I don't have to worry about the onset of the warmer weather for a couple more months.

According to the data in the article, the average light output of Phoenix bulbs levels out to 75% after 6 months of use. At one year mark it is at 93% of what it had been at 6 month mark. The bulbs retain 70% of the original radiance at 18 months.

This could lead to a significant saving .

Tomoko

 

[buzzbait00]

Hey Tomoko!
I have noticed that the tentacles on some of my zoanthids have went from straight to curly(looks like they got a perm!)They are all opened up good though.Is this normal or could something be wrong?I have changed a few bulbs and bumped my alk resentily but thats about it.Could it be the new bulbs?

 

[Tomoko Schum]

I don't really know if the curly skirts of your zoanthid is related to light or not. My blue zoanthids have small faces with short straight tentacles. I noticed that the same blue zoanthids had much bigger faces and longer curly tentacles in Lori's tank. My tank is much shallower and more light seems to reaches the zoanthids to keep them small. However, I suspect that there are other factors that can make zoanthid look different such as genetics. A big change in alkalinity seems to affect zoanthids as well. As long as the water parameters are in acceptable ranges and your zoanthids are fully open and healthy looking, I would not worry about it too much.

Tomoko

 

[6Speed]

I've got my bulbs at least 1 foot over the water. I always thought the distance above water wasn't so much important (within reason), as the distance below the surface? What I mean is that the light loses intensity very quickly the more water it has to pass through, as opposed to it not losing intensity as quickly when passing through air.

 

[Tomoko Schum]

6Speed -

Here's what Dr. Joshi wrote about the light lost to distance in air vs. light lost in distance in water:

"Most of the SPS and other corals in our reefs are found in waters less than 15-20 meters deep, but our reef aquariums are usually only 24 to 30 inches deep. At this depth of water, the amount of light lost to absorption by the water is quite small. -- snip-- Further more in our aquariums, the primary cause of light drop off is due to the "inverse square law". This drop due to the distance from the source of light is much higher than the absorption in the water."

If the distance is doubled, the irradiance is reduced to a 1/4 of the value at the original distance according to the inverse square law. (PPFD1/PPFD2 = (D2/D1)^2.)

I have both my 250W 14K bulbs at 8 inches from the water surface. I do not know the strength of your bulbs, but if it's 250W x 2, my tank appears probably 4 times as bright as yours to my corals.

I recall Philip once saying that his coral frags look really brightly colored and nice under 1000W bulbs in one of his customers' shops (Cappuccino Bay in Atlanta?.) I was really envious of the amount of PAR values he quoted. I suspect that I am still far from that, but my corals look very happy. They seem to be able to adapt to various light conditions very well over time. It's amazing, isn't it? I went through this exercise mainly to match the light levels of my new bulbs to that of my old bulbs so I won't bleach my corals.

Tomoko

 

[6Speed]

Well I guess I shall be lowering my bulbs very soon! I hate to do it, though, b/c the lower they are, the easier they are to touch when you're working on the tank!

 

[Tomoko Schum]

You're probably right about the light fixture being in the way. I guess I am used to having the light fixture at that height. I have not found my light fixture to be bothersome to work around. If you are handy like 8Ball, you can put your canopy on linear guides so you can raise it up and down easily.

Tomoko

 

[KwajRocks]

Tomoko, Funny you should mention the blue zoanthids you gave me. After we talked about the differences in them between our tanks, I moved them up to the top of the tank recently to see what effect more PAR would have on them. Although I do not have a lux meter, and am unable to measure the PAR, I am assuming that they are receiving more since the distance is about 30" closer to the lights. (i.e., I cannot take into account the effects of the reflectors). On the newest growth, the faces on the zoanthids are smaller, and the tentacles on all the new growth and the existing, have shortened and straigtened out. This may confirm your theory about light and these zoas. As far as the color, oddly enough, I cannot see a big difference.

 

[Tomoko Schum]

That's very interesting, Lori. I wonder if Buzz can reproduce the same thing by bringing up the zoanthids closer to light.

As for the color, I had to move the blue zoanthids around a bit to find the location that they look the best. They seem to color up better in the shadier side of my tank where the light appears bluer. My pink Capnella seems to have cooler pink there as well.

Tomoko

 

[8BALL_99]

<a href=showthread.php?s=&postid=9704697#post9704697 target=_blank>Originally posted</a> by Tomoko Schum
You're probably right about the light fixture being in the way. I guess I am used to having the light fixture at that height. I have not found my light fixture to be bothersome to work around. If you are handy like 8Ball, you can put your canopy on linear guides so you can raise it up and down easily.

Tomoko

Haha TY. It does make it super easy to work on the tank.. Not to mention raise my lights up come new bulb time

I keep my Lights very low.. As low as I feel is safe infact. The bottem of my Reflectors are only a few inches off the water. My bulbs on the other hand are probably 8" or so off the water.. I figure if your going to pay for the electricity to run the bulbs you might as well get the most of them. I just always move the corals around till they seem to be happy. Most everything seems to do fine at the top though, as long as you move them up over time. I was worried about corals right under my 400 watt bulbs at first, But so far I haven't knowticed any of them have any problems with it.. Heck I've even got baby Kenya Trees popping up at the very top of my 180 between a 250watt mh and a 400 watt mh

Will

 

[KwajRocks]

I agree with the bluer light coloring everything up. I kept questioning in my mind (and still do) that in higher light (10ks vs. 14s) whether the SPSs are producing more zoox to gather more available light, or they are browning up to protect themselves. With my 10ks, brownish was the color of the day, although the growth rate was accelerated. With the new 14ks everything colors up in the blue shades (which includes the pinks). The zoas you gave me do look blue in the 14s. Currently I have a mix of 14s and one 10k left on each tank - mostly for a depth perception effect. I know some do not like mixed bulbs, but for my tanks, I think they look cool.
The corals I inherited from Chris were the most gorgeous colors you have ever seen in his tanks (20ks). He also had high growth rates with this color. In my tanks, they were not as colorful, thus the switch to 14s. I also added another 110w super actinic.
No question in my mind that the bluer the lights, the bluer the corals, but you lose a bit in growth rate.
Is this something everyone knew already, and I just had to learn on my own? Again?

 

[KwajRocks]

Will, kill that Kenya while you have the chance.

 

[Tomoko Schum]

Yeah, kill that thing, if it's a whispy looking Capnella. It's just as bad as the pink plague (pom pom xenia) of mine. It drops its branches and you'll have the little pink weeds popping up everywhere. Xenia mainly climbs upward and leaves trails of babies behind. The type of Capnella some of us have will drop their offspring to blow around and lodge themselves in most inopportune places in the tank.

Cladiella is also called Kenya tree sometimes. It's also called Colt and finger leather, too. This one is not as invasive as Capnella.

Tomoko

 

[buzzbait00]

after closer inspection,I think the skirts on my eagle eye colony look curly is becouse of light.I had used bulbs and didnt know how old they were.Over the past several months I have replaced all of my bulbs.6x54 on 3 work horse 5's Blue plus,10k,super actinic,10k,blue plus,10k.I now notice that the skirts are curly,shorter and the polyps have retracted alot.The whole colony looks smaller but more vivid colors.Yea!I've got zoanthid frags that came from under strong lights that looked like pin heads.Put them in the sand with my old bulbs and they streached waaaaay out.Heads got bigger!Ive got frags off the same colony at the same time.put one in the sand ond one 3/4 up.They look alot different.I personaly like um streached out!