jolliolli Posted December 2, 2007 Report Share Posted December 2, 2007 Got my new toy this week my Oceanlight MH pendant, this model here http://www.aqua-medic.com/oceanlight_T5_HQI_combo.shtml the 4ft version with the 2 x 250WMH. Anyway so this weekend my partners looking to mount it to suspend it above the tank for me. We have a coved ceiling. Directly above the middle of the tank is where the cove starts and the ceiling changes heights. We were thinking of drilling holes the width of the suspension cables through the cove and mounting a piece of 2x4 wood in the ceiling space. Cables will pass through the cove and instead of mounting directly in the beams will keep going until they reach the mounted 2x4 and connect to this. Does this sound Ok, is there any other better way? Quote Link to comment Share on other sites More sharing options...
davidb Posted December 3, 2007 Report Share Posted December 3, 2007 thats what alot of people do Quote Link to comment Share on other sites More sharing options...
jolliolli Posted December 15, 2007 Author Report Share Posted December 15, 2007 Few more questions on metal halides. Put them up today and i'm wondering what the best height would be. Instructions recommed 6 - 12 inches from the water surface. Tank depth to base of sand bed is 53cm. Currently they are mounted 22cm from the surface, is this the right height? Below is a picture of the tank prior to the lights going up i think i'll need to rearrange the position of the corals so that some of them don't get bleached. Can ppl recommend what height they would put the different corals at? I suspect the clam (and rock its on) may need to go to the sand bed and the bubble coral lower down? Also has anyone had experience running MH lights on the juwel tanks (or any tanks with plastic bracing across the tank?). I have two plastic braces running across the tank, they get quite hot and i'm worried about them snapping due to heat (i've had this happen on my other tank). has anyone else had them snap? I can't move the braces as they're glued in place. Any suggestions appreciated Quote Link to comment Share on other sites More sharing options...
wasp Posted December 15, 2007 Report Share Posted December 15, 2007 Your 22 cm is a good safe hight for now. You could go lower but you have a lot of softies & lps, I would gauge it by the effect on them. If they get too much light they will contract in size, so you will be able to tell what is right for each one. Contracting in size is not nessecarily bad for them mine are a bit over lit but continue to grow well. But they look nicer a bit spread out. The clam will actually like a lot of light. Can't answer the question about the braces but does sound like you should seek further advice on this, as the consequences of a failure could be nasty. Quote Link to comment Share on other sites More sharing options...
jolliolli Posted December 15, 2007 Author Report Share Posted December 15, 2007 ok thanks wasp, i had considered moving the lights to 30cm but if 22 is ok then i'll stick with that for now. The lighting intensity has been tripled and i wondered whether such a sudden increase could send the corals in to shock? one thing i considered doing with the braces is covering them in something to prevent them heating up, maybe wetsuit material or something similar? I may end up moving the clam anyway as its not really showing it off where it is, the position its in at the mo makes it look brown, if i move it lower down the tank it gets it makes the blue highlights visible. Noob question for you, if you have a fixture that takes 250W bulbs can you use lower wattage bulbs in them? Quote Link to comment Share on other sites More sharing options...
reef Posted December 15, 2007 Report Share Posted December 15, 2007 Noob question for you, if you have a fixture that takes 250W bulbs can you use lower wattage bulbs in them? no. you need to change the ballast and the connections. i doubt the bracing will be a problem, especially if the halide are 22cm above the water Quote Link to comment Share on other sites More sharing options...
Rockerpeller Posted December 15, 2007 Report Share Posted December 15, 2007 according to the electrician that organised my halides, it is possible to run smaller bulbs. although he did say that it would shorten their life expectancy. Quote Link to comment Share on other sites More sharing options...
reef Posted December 15, 2007 Report Share Posted December 15, 2007 A bit difficult as the fittings are not the same. 150w bulbs have rx7 holders 250w have fc2 fittings, Also Never run 150w bulb with 250w bulb ballast it will change the spectrum of the bulbs by overdriving them. Quote Link to comment Share on other sites More sharing options...
Rockerpeller Posted December 15, 2007 Report Share Posted December 15, 2007 A bit difficult as the fittings are not the same. 150w bulbs have rx7 holders 250w have fc2 fittings, Also Never run 150w bulb with 250w bulb ballast it will change the spectrum of the bulbs by overdriving them. Yeah thats what i heard as well while browsing various sites. how much of a boost in the spectrum will it create tho? sorry for thread hijacking :oops: Quote Link to comment Share on other sites More sharing options...
reef Posted December 15, 2007 Report Share Posted December 15, 2007 I am not sure, but it will overdrive the bulbs. also the starters wont match , the bulbs so they could blow up or arc, very dangerous. Quote Link to comment Share on other sites More sharing options...
jolliolli Posted December 16, 2007 Author Report Share Posted December 16, 2007 all good info thanks. Bought some black foam to put on the plastic bracing as a precaution. Last time the plastic brace snapped on my FW tank it caused some drama so don't want to risk it again. Also bought 4 additional fans to disperse some of the heat from the MHs Quote Link to comment Share on other sites More sharing options...
cookie extreme Posted December 16, 2007 Report Share Posted December 16, 2007 also the starters wont match the starters will, as almost all starters these days are good for 150 - 400 or even 1000 watt. but nothing else will. as reef said wrong fittings and ballasts. don't really want a bulb exploding over your tank do you? Quote Link to comment Share on other sites More sharing options...
jolliolli Posted December 16, 2007 Author Report Share Posted December 16, 2007 no not going to even try it, was just interested to know Quote Link to comment Share on other sites More sharing options...
Zhacque Posted December 16, 2007 Report Share Posted December 16, 2007 All good advice given. I'm an electrician, and using incorrect fittings or start gear will seriously reduce the life of the bulb, reduce it's performance, and could (as Reef said) cause the bulb to explode. There are other possibilities such as wiring overheating ("What's that burning smell?"!) Or the bulb terminals arcing due to inadequate connections. It's simply not worth the risk! But I see you've taken everyone's advice already! 8) Quote Link to comment Share on other sites More sharing options...
Ira Posted December 17, 2007 Report Share Posted December 17, 2007 Do 150w and 250w MHs run at different voltages at the bulb terminal ends? Quote Link to comment Share on other sites More sharing options...
slappers Posted December 17, 2007 Report Share Posted December 17, 2007 1 got a arcadia 3 pendent, it used two have two 250w MH bulbs,but i found it FAR TO BRIGHT for what i needed all that i had to change was the fittings and the ballasts, starters were sweet, i did have a sparky check it over to be on the safe side Quote Link to comment Share on other sites More sharing options...
tiri Posted December 17, 2007 Report Share Posted December 17, 2007 It varies across brands, but is in the range of 90 to 110 volts and 2.8 to 3.2 amps. 400W runs around 135V and 3.3 amps. There's one out now that switches between 250W and 150W, at the ballast. Can't see the use, though, as to change requires bulb holders, and worse, reflectors which never fit. Quote Link to comment Share on other sites More sharing options...
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