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Metal Halide vs. CO2


antwan

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I have been told by a few different people that CO2 is better, and by others that MH lighting is better. So, i would like to judge my decision from the responses i get off this post.

I have a 162L fully planted tank running at the moment, however, i want the plants going even better. I only have approx 0.62 WpL at the moment. If i can i would rather go MH because it will be easier. i went to the lfs today and they can do me a second hand 150W for $150, and am getting a price on a 250W as we speak. If i go MH do i need to go 250W or will just 150W do?

I think that's all i wanted to say, anyways any and all help will be most appreciated, thankyou.

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Strewth!! IMO On a tank that small a 150W MH is overkill. For a planted tank you will have difficulty finding a bulb the right colour - they are available tho...

But the biggest issue you will find is balance, you have to do everything together. If you go to 1 WPL ( with a 150W) you will still need CO2, ferts etc... There is no 1 single 'pill' that will make you plants grow better.

Increase your lights a bit, by adding another tube or two, make sure all the tubes are up to spec ( less than 6 months old). Add some DIY CO2. Get some good liquid fertilizer and do everything in balance

HTH

DJ

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Well said, DiverJOhn.

150w over 162 litre is an over kill. 100w will do fine for your tank.

How much light and co2 also depend of how well cover is your plant in the tank.

to have a lush green effect, you will need a good balance of light, CO2 and fertiliser.

DIY CO2 is unstable and will eventually cause bad algae growth.

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Neither is better, they go hand-in-hand...

In saying that, MH on a tank that size is probably not necessary unless you want to go MH for the sake of it. Fluro's will work just as well unless the tank is over 600mm deep then MH will help a bit.

CO2 and lighting are a balance, you don't need one without the other. Adding CO2 without the correct lighting will do very little and adding the correct lighting without CO2 is much the same and you may end up with unwanted algae...

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I'd go for the 250w, this way the plants spend less energy trying to get light, and more trying to get CO2 and other nutrients which can be added. I saw a great graph of this on the net, I'll try and find it. Like Warren said everything is important but it goes like this in order of importance:

Light

CO2

Iron

Other nutrients, PO4, NO3, K etc (macro/micro)

1W / litre is not overkill, I'd say that's target. Any aqua scaping contest will show many tanks that have way over 1W/litre particularly in the smaller tank range.

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ok, on this topic on my tank 220L would a 250W MH be over kill? i have no c02 at all and dont want it right now so i think it might not be right for me however if i dont get it im getting 3 36W tubes (fluros)/ maybe a 150W MH. ive got all the ferts but c02 isnt in the top 5 'to do' list. i have aquatic mix down, with jbl 7s balls for special plants and use flourish excel/lukes ferts. so all you plant books let me know which would be right for me hehe

p.s. sorry to hijack ant! you can punch me on saturday lol

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came up with 111W for mine so my fluros would be sweet? thats pretty wierd how bigger bodies need less light (thats what its saying right), why would a smaller space need so much more, surely all plants need the same amount of light whether theyre in a big or small tank? definatly something to think about, cool link DJ!

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Yes it is interesting. Really goes to show that there are a few variables to consider, like Warren said depth is a consideration... but not the only one.

You need to consider intensity, colour of light, duration, tank volume, depth, mix of plants, fish and lastly.... what you want! If you were trying really hard to mimic nature then maybe an hour or two a day with a 150W MH and 100W worth of flouro's might help.

But over all you need to SIBKIS (See it big, Keep it Simple). You cant really beat flouro's for ease of use, the availablity of replacement parts, different colours, and over all cost. Particularly when you are looking at less than 250watts total.

DJ

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I would definately say go CO2 - it is most likely the limiting factor in your plant growth. Whats the point of extra photosynthesis if there isnt any carbon to make glucose from. -There isnt, and photosynthesis will stop.

Although saying that I dont know comparativly how much light your putting out. Why dont you just get cheap flouros and CO2.

I think MH is overkill, plenty of really green tanks out there with tubes.

CO2 actually allows your plant to build mass, while light only provides energy to allow the uptake of CO2.

Id hit the first one - unless of course you have really low light levels - in which case get some new tubes - then C02.

My friend diy'd a co2 reactor - his plants went REALLY nuts.

My suggestion would be to build a crap one like he did - for free out of a coke bottle, and then make your decision after you are wowed by the results.

:D

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MH is the way to really get your plants cranking. For example, in my tank with pressurised CO2, the plants don't off-gas/pearl O2 with the fluro tubes until evening when the lights have been on a long time. If I put the 400w MH on it doesn't off-gas O2 straight away but it does it hours sooner and the bubbles are much more proficient, meaning the growth is much better and the greater mass of bubbles are really neat to see.

MH power is the only way to really get ground cover plants going nuts too, but this does depend on the depth of the tank.

In summary you can get away with fluros fine and have good growth, but MH IMO is much more effective.

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Ok, well i think i will go MH (sorry to others), i have seen lukes tank and it looks completely awesome. I know with them i will finally be able to get my ground cover plants going well. Then, if im not totally getting what i want, il reach out for CO2. It's just the ongoing costs of CO2 that is a pain. I am only 16 and making $130 a week, so i dont really want additional costs. Thankyou for everyones comments, they are greatly appreciated :D

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Dude running 250W Mh's have some pretty serious ongoing costs. :D

If you go the MH way just diy a cheap co2 unit - you dont need a fancy cylinder -and it will work really well. All you need is some tubing, a coke bottle, sugar and yeast. Pretty much free.

Then you plants will really go nuts

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wot kind of costs does MH possess, apart from replacing the bulbs of course? I have one of those nutrafin CO2 yeast thingys, but took it out as i was seeing absolutely no results... Shall i chuck it back in just for the sake of it? guess it wouldnt hurt....

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now to hijack again (does this mean two punches ant? lol). $150 a year is too much for me to pay so im thinking a 150W mh and my 36W tube. giving me a total of 186W for a 220L tank (take out L for gravel etc). is this a pretty good average? id only be getting 108W off my three fluros ill be running otherwise. my tank is 42cm deep.

in the long run, taking into account power usage and replacement costs of bulbs/how long they run for before replacing will it work out cheaper with MH and fluro or will the 3 fluros cost less? its going to cost me at least 100 or so anyway to get a double tuber and the tubes to go in it if i go the plain fluro way.

thanks to all :hail:

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Sharn your fluros would work out cheaper as MH bulbs are $80-100 each usually, but 186w would be really nice for that tank and get some awesome results you wouldn't get with just the fluros. Depends if you want to go low-tech or high-tech as aquatic gardeners call it. I.e high-tech is high light/CO2/nutrients/growth or low-tech is vice versa.

Below is the link I was mentioning earlier about the factors that are most important for plant growth. As you will see max CO2 and light gets the best growth; they've cleverly worked out a growth points system too. So max CO2/light gets 14.8, max light and moderate CO2 gets 6.5, and moderate light max CO2 gets 4.1. Whichever there is a lack of the plant must spend more resources focusing on it. When it is abundant that is when it can just concentrate on growing.

http://www.qsl.net/w2wdx/aquaria/diyco2.html (first graph, about 1/8th of the way down). Further down is also a calculation for working out how much CO2 is in your tank and the desired range. There's also a lot of info on producing CO2 and different methods for creating DIY CO2 diffusion into your tank. Hope you all find it useful.

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thanks luke! do MH lights last longer though? if im replacing three tubes every 6 months at say 20 each thats 60 or so but its worth the 40 odd extra to have extra watts. so id spend around 120 a year on bulbs compared to 100 or so every ... months

spose it just comes down to what i want after i read up some more :roll:

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MH lights last i think for about 10,000 hours. That is what my boss told me (he has them in his shop, and they are 75W). So, if you have your lights on for about 10hours a day the bulb should last approx 2.8 years.

However, do MHs need replacing after a certain period of time like fluoros?

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if im replacing three tubes every 6 months at say 20 each thats 60 or so but its worth the 40 odd extra to have extra watts.

:o I only pay about $5.00 a tube from bunnings, those flash grow tubes are not really necessary........ but then that is a whole new thread 8)

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DiverJohn the bulb I got with it came with it, I was told it's about 6500k and that would be pretty accurate I'd say because it's a nice white light colour that looks natural.

Sharn my understanding is that MH bulbs last about one year. So if you did buy the more expensive fluro bulbs at $20 each, that's $60/6months = $120/year which is even more than what the MH bulb (approx $100) would cost you per year!

Ant, no worries lots of good info there and interesting e.g champagne yeast lasts a lot longer than brewers so you get more CO2 out of it before having to change the mix. Also that baking soda has no impact over CO2 production, it has proven to have survived in high acid and alkaline situations (people use to think and some still do think that the acid kills the yeast, not true, it is the alcohol that does)

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