Mh Over A Planted Tank

[Murminator]

Is anyone running metal halides over a planted tank? After 10 years my reef tank is really starting to tick me off might scrap it a do a planted tank. Would the plants melt? it is currently running 2X250W over a 90G so 5.5w per gallon too much? I haven't heard of anyone running MH over planted just wondering if it can be done

Edited April 26, 2011 by Murminator

[ridethespiral]

Sounds like algae heaven.

You could maybe get away with one of the pendants raised high up, but would still have to inject CO2 and fertilize.

I run 2x54w T5HO over my 75g for 10hrs, but have it raised 12" above the tank in order to avoid the need for CO2 injection and fertilizing. Plants really don't need as much light as reefs

[ubr0ke]

Its possible but like ridethespiral said its going to have to be raised quite high above the tank. light needs to be the limiting factor since its controls the uptake of nutrients...co2 included...the more light the more co2 you need..the more co2 the more macros and micros, in that order. Too much light and you will never be able to supply enough co2 and algae will appear..

ada tanks use mh lights but after measuring lights with a par meter it was discovered that there fixtures put out about half of what a typical mh lamp does...

We should all pitch in a few dollars from this forum and purchase a community par meter and end all the confusion when it comes to light. I posted a chart that takes some of the guess work out choosing what lights to use but actual par readings vary from fixture to fixture. A par meter roughly cost around $300 so it wouldnt take much..

[jcgd]

I agree with urbroke. Lots of people use mh. If your fixture has t5ho use them and the mhs for a midday burst.

[jewels]

Is anyone running metal halides over a planted tank?

Yes, I have a single 400 Watt Ushio MH sitting over one side - right on the glass, on a 75 gallon.

Has been running like that for a couple years now.

All it takes is a ton of CO₂, and a realllly strong stomach.

It can be problematic, although it can be done.

Yes, we have seen these photos before.

But I like 'em :tongue:

[ubr0ke]

jewels do you limit phosphates?

[werner]

I also use MH: 2 x 150W (+ 2x 54W T5HO) on a 120 gal. The T5HOs are on all day and the MH is only on for about 5-6 hours in the middle of the day.

[jewels]

jewels do you limit phosphates?

Potassium

[ubr0ke]

Potassium???...umm..im guessing thats sarcasm.

[jcgd]

jewels do you limit phosphates?

Do you? If so, why?

Sorry to highjack.

[ubr0ke]

I dont....

The reason you would limit phosphates is because of a direct relationship with co2 demand...With phosphates less light is needed but co2 demand is higher...With limited phosphates less co2 is needed but more energy(light) is needed for photosynthesis. Pmdd was a fert dosing stragedy involving limiting phospahtes. Phosphates were thought to cause algae but what was really the problem was limiting co2 levels. Phosphates increase demand and when those demands were not met with co2, algae followed.. So now we add co2 plus phosphates and as long as your co2 is non limiting then phospahtes are not a problem. This only works with phosphates not with nitrates or potassium because of the direct relation. It makes more sense to add co2 then it does to limit phosphates for many reasons. Cost is one...ferts and co2 are cheap. Electricity and bulbs are not. The extra energy(light) needed when limiting phosphates is a waste. Another problem is that it doesnt work with all plants...typically stem plants are fine but more co2 sensitive species need an enriched co2 enviroment plus phosphates to take advantage of that co2.

The high light myth and phosphates cause algae myth were based on a theory which many have proved not the case..So its kind of an old way of thinking but many still use these methods..

MCI is a method that still uses this theory...Its about chasing defficiencies rather then growing plants...

Using ei is much easier and can also be scaled back to just supply intake simply by lowerig dosing amounts until you see deficiencies. Then increase dosing a little bit and your good..Slowly increase as plant mass increases..Id rather simplify somthing that works then chase deficiencies any day.

Edited April 27, 2011 by ubr0ke

[jcgd]

Using ei is much easier and can also be scaled back to just supply intake simply by lowerig dosing amounts until you see deficiencies. Then increase dosing a little bit and your good..Slowly increase as plant mass increases..Id rather simplify somthing that works then chase deficiencies any day.

Thanks for the explanation. I agree that EI is much easier and I also use the method of ei, and scaling back until deficiencies are seen (although I often can't be bothered to even scale back, just stick with full estimated dose). I wish I could get people to stop thinking they need more light, or the 3wpg. That 'rule' really screws people up. Some seem to think the $150 light is cheaper than the $150 co2 setup. Hehe.

[ubr0ke]

I totally agree but all we can do is try to change their minds one post at a time.....

also sorry for the hi jack.