Yes, I hear you... I had to get a 1/4hp chiller to put on my 15gal planted tank because of the heat from the MH's. <Grin> But I look at it this way... now if I ever decide to do a salt water tank, I'm set. However, I am curious about all your maintenance issues with your MH's. I've been running mine for the last six years and I've only had to replace the bulbs every few years. Were you using electronic ballasts? And yes, I totally agree, you have to think ahead and plan for when you are going to need parts. The bulbs I decided on are VERY hard to find ANYWHERE... I end up having to order them directly from Philips.Thanks for sharing that info. Here is my subjective 2 cents having used a pair of 175 watt MH pendents over my 55 for 10 years or so. They generate a lot of heat-so much in fact that I've always toyed with the idea of getting a small chiller. The bulbs are hard to find locally and are expensive-also they don't seem to last very long. The ballasts need replacing periodically as do the sockets. If you don't have back up parts your plants will go without light while you wait for UPS to arrive. That being said, they do look nice, specifically the light they provide. I got tired of replacing bulbs and rebuilding ballasts-I now have a Hagen GLO T5 fixture and I'll no longer look lustingly at chillers in catalogs.
Thanks CL... Well, if you decide to go down that route understand that heat is a huge issue. Even in an air conditioned room, MH's dump too much heat into the water. It might be somewhat less of an issue with larger tanks (100gal+), but with the smaller variety the lights have to be well vented and fan cooled... to the extreme of using a chiller. And I cannot overstress that all MH bulbs are not created equal. They come in many different forms to meet the needs of several different industries, mostly which revolves around commercial and industrial lighting. When shopping for MH bulbs, choose bulbs that have a high color rendition index, preferably above 90CRI (100 is the max, and if a MH bulb was rated at 100CRI, it would perfectly match sunlight.) I coudln't find what I was looking for in most MH lights designed for aquariums which is why I went the complete DIY route... and any which way you look at it, it is expensive. Also, most of the MH lights you see on reef tanks do not have the sunlight quality I am refering to, they are shifted heavily blue/green - perhaps because of their efficiency of penetrating deeper waters, or simply perhaps because they are cheaper to make.Excellent post as always, 4x4. You definitely almost have me convinced to use MH over my tank that I'll be setting up shortly. What you said makes perfect sense about the blending between different wavelengths of light that MH has as opposed to fluorescent lights, and that never occurred to me. :thumbsup:
T5HOs also don't produce as much heat as MH's do,
T5HOs and MHs have similar efficiency. Some of the power put in is converted into light and most is converted into heat. I.e.: same power bulbs (one of each), similar light and similar heat.the cons of MH are the heat they produce and their uneven distribution of light into the tank.
No, they aren't electronic. I would imagine that they are less problematic. Perhaps my problems are age related-they are at least 10 years old. Connections in the sockets get corroded, the plastic grommets that hold the cord in the top (and supports the fixture) get brittle/crack and become non-functional. They are finicky about being slighlty underpowered eg: at home the 111-112 volts at my outlet won't fire them on while if plugged into a good 115v outlet they will. Good bulbs are expensive. As another poster said they are not hotter than fluorescent-maybe not per watt. But to cover a 4 foot wide tank you need 2 fixtures and a 175 mh pendent does get hot-very hot. I do love the look of them though.Yes, I hear you... I had to get a 1/4hp chiller to put on my 15gal planted tank because of the heat from the MH's. <Grin> But I look at it this way... now if I ever decide to do a salt water tank, I'm set. However, I am curious about all your maintenance issues with your MH's. I've been running mine for the last six years and I've only had to replace the bulbs every few years. Were you using electronic ballasts? And yes, I totally agree, you have to think ahead and plan for when you are going to need parts. The bulbs I decided on are VERY hard to find ANYWHERE... I end up having to order them directly from Philips.
Touche :icon_winkT5HOs and MHs have similar efficiency. Some of the power put in is converted into light and most is converted into heat. I.e.: same power bulbs (one of each), similar light and similar heat.
The issue is that MHs get hot in one spot whereas T5HOs are spread out and the air takes the heat away so much more quickly.
To push a point, where MHs are just slightly more efficient and furthermore produce just slightly more useable wavelengths one could say that for similar growth of the plants, MHs in fact produce less heat.
I do not replace mine every six months. But the warning is this: Some MH bulb types (ED17, for example) simply do not "go out" at the end of their life.... they explode, or CAN explode. This is why most bulbs have to be in a rated enclosed fixture. Commercial applications of MH bulbs have a routine replacement schedule to avoid the problem of exploding bulbs, think your local Costco or HomeDepot which use MH bulbs located in the rafters.Is it true that mh bulbs should be replaced every 6 months? I love the shimmering effect but, the cost of mh is just daunting.
Sure, I've had my learning curve with algae. But once I learned about the mechanics of a proper substrate, and about PAR values, algae is now very minimal. Usually what gets me is that I don't trim and prune enough. I love to see the vibrant growth and don't want to cut a plant down, but soon the large plant mass shifts the dynamics of the tank. It changes the water flow, and hence the CO2 distribution; and it changes the amount of light reaching the lower plants. And, it creates excessive dissolved organic carbon, from decomposing plant matter.4x4, just wondering if you ever have some crazy algae outbreaks or a lot of maintenance with that much light?