How high do you hang your metal halide set?

[o2bubble]

Hi guys, not sure if this is an old topic.... I'm currently hanging my 2x150w MH 25 cm above my tank of 4x1.5x2ft and saw much improvements on my plants growth and color when they were at 30 cm previously. I saw some display tanks (biotope, midori etc) hanging their lights only at about 20 cm instead and the red plants shown good colors and even the rotala sp green leaves are slightly smaller (not sure if due to this). Are there any side effects (e.g. burnt plants, algae, not enough area coverage) with 20 cm height..

So, I'm posting a poll here to gather some feedbacks for the benefits of all those using or intending to use MH

[salexjared]

I am not hanging mine 300W (2x150) but using the stand that came with it (for 3ft). Please are growing better but some seems to see browning (burn) and algae seems to become a problem.

I only on for 2.5hrs in the afternoon and 3hrs at night.
Is that too much ?

Do I need to put it higher up. It is now around 15cm above the water level.

[Goondoo]

I find 30cm and above best as they spread out the best. When my lights were hung between 20-25cm, I find the plants directly under the lights grew a lot faster than those at the sides and corners.

[o2bubble]

I saw in some website that explains about MH and it recommends at least 20 cm above water or the plants might get "burnt".

Maybe you can try to hang the light with a light stand or find a suitable higher pair of side holders?

I am not hanging mine 300W (2x150) but using the stand that came with it (for 3ft). Please are growing better but some seems to see browning (burn) and algae seems to become a problem.

I only on for 2.5hrs in the afternoon and 3hrs at night.
Is that too much ?

Do I need to put it higher up. It is now around 15cm above the water level.

[o2bubble]

Same experience as well when I was hanging at 30 cm but it's ok for me as my high light plants are in the centre and sides are mainly rotala green, Fern and crypts.

The question I have in mind is actually does hanging lower increase the intensity of the light for MH since MH can penetrate up to 3ft (correct me if wrong), thus improving the color of the plants and making my e.tellenus stay smaller (currently around 4-5 cm avg, hoping to get around 3-4 cm tall)..

I find 30cm and above best as they spread out the best. When my lights were hung between 20-25cm, I find the plants directly under the lights grew a lot faster than those at the sides and corners.

[bubberls™]

I have mine 2x150w hanging at 23cm and so far everything ok except for my Tonina sp which seems to be having problems. not sure if it is the light. hanging at this height also seems to heat up the tank a lot too.

[adeguay]

I hang my 2X 150W at 30 cm from water level. So far no problem but still not able to get HC grow on my tank. HC alway melt.

[bubberls™]

adeguay i have HC too and they seem fine... not growing very fast but least it is creeping... maybe lower it a bit might help since we both have 2x150w

[adeguay]

adeguay i have HC too and they seem fine... not growing very fast but least it is creeping... maybe lower it a bit might help since we both have 2x150w

Thank for your tip.

Beside 2X150W MH, I also have 2X 54W T5.

I have try 3 times on HC. So far no luck at all. Well keep on trying.

I treat this as my goal for the planted tank. If not nothing to look forward now.

[bubberls™]

no prob bro... i believe you HC will grow this time... oh yah watch your NPK doses. It plays an important factor.

Mine grows ok but not crazy fast growth like i see in some forums... as far as i know it takes me about 2-3 mths to have a nice lawn... 2-3 weeks is kinda impossible for me.

[Kristen]

Just a question from a n00b - Am currently using 2 tubes of T5HO lights, and I know this is not enough. I want to buy the BOYU light set with 2 T5HO lights (which I plan to change to pink and blue spectrums) + 2 MH lights. I know this is strong and I have Tiger Lily leaves on the surface of my water.

What is the optimum height to hang the lights?

Is it necessary for me to hang the lights from those metal bars I see on sale at Mizu world?

My tank is rather tall so I need MH However, will it burn my pretty tiger lily floating leaves?

Thank you in advance for helping the n00b ;-;

[zhuzhu]

Same experience as well when I was hanging at 30 cm but it's ok for me as my high light plants are in the centre and sides are mainly rotala green, Fern and crypts.

The question I have in mind is actually does hanging lower increase the intensity of the light for MH since MH can penetrate up to 3ft (correct me if wrong), thus improving the color of the plants and making my e.tellenus stay smaller (currently around 4-5 cm avg, hoping to get around 3-4 cm tall)..

May I know what is the kelvin used for your MH?
Mine is 14 000 k

[carlfsk]

The question I have in mind is actually does hanging lower increase the intensity of the light for MH since MH can penetrate up to 3ft (correct me if wrong), thus improving the color of the plants and making my e.tellenus stay smaller (currently around 4-5 cm avg, hoping to get around 3-4 cm tall)..

I tend to observe that whether e. tenellus grows long / high or short / low is dependent on the richness of nutrients in the gravel.

I have some growing directly underneath the 150 watt MH and they grow pretty long (maybe 8cm). This tank is a new setup with new base fert. This is a 2ft deep tank.

While those I had in my office growing under 2 25watt FL tube stays short / low. The tank in my office have very low nutrient in the gravel, as the tank has been around for quite a while. This is a 1ft deep tank.

BTW, I hang my MH about 10inch above the water level. If taking into consideration of the exact distance of the bulb and water level, it should be 1ft gap.

[StanChung]

I think too low <20cm the intensity is not spread and you can see the cone shape light rays in the tank.
I think ideally it should be at least 20-40cm. Depending on the dimensions of you tank and your aspirations. Some of you want more intensity to reach the bottom and also want to tan the plants while some just want one MH bulb to take care of the whole tank.

I have 2X150W + 4X36 hanging around 40cm for a 5X2X2 height tank. This is a little too high and it's hard to plant any foreground plants. The height of the tank is a big factor.
The other 3ft tank has 150W+2X36W hanging at around 40cm. It's high enough to cover the whole tank and the intensity is enough to grow Japanese hairgrass. This tank gets substantial window light. Ideally I'd like to lower the gap to 25-30cm.

[Goondoo]

I think too low <20cm the intensity is not spread and you can see the cone shape light rays in the tank.
I think ideally it should be at least 20-40cm. Depending on the dimensions of you tank and your aspirations. Some of you want more intensity to reach the bottom and also want to tan the plants while some just want one MH bulb to take care of the whole tank.

I have 2X150W + 4X36 hanging around 40cm for a 5X2X2 height tank. This is a little too high and it's hard to plant any foreground plants. The height of the tank is a big factor.
The other 3ft tank has 150W+2X36W hanging at around 40cm. It's high enough to cover the whole tank and the intensity is enough to grow Japanese hairgrass. This tank gets substantial window light. Ideally I'd like to lower the gap to 25-30cm.

Talking about delayed replies........

[StanChung]

Hehe-somebody resurrected the poll by voting on it. Just noticed the dates. oops. Seemed like a fresh poll.