Very high light problem

mannwhite

Junior Poster
Feb 17, 2009
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Hi all,

After going way overboard in my calculations I ended up having 300W MH in my 50gal tank giving me near as makes no difference 6wpg. I have CO2 fert and use Ocean Nutrition Fertil+ and Trace+ for my macros and micros (except NO3 and PO4.

I have 2 questions

EI states that if u have high light you can go the next step up, will this be enough for me?

If I dose double the nitrates and phosphates as per EI should I also dose double the Fertil+ and Trace+ or should I always follow the instructions on the bottle?

Thanks and regards
Adrian
 

VaughnH

Lifetime Charter Member
Lifetime Member
Jan 24, 2005
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Sacramento, CA
I'm not sure just how much light you actually have. I'm assuming you have the MH lights suspended above the tank, so the intensity depends on how high they are suspended. Assuming you really do have very high intensity, CO2 is the biggest problem you will have to solve. That light will be driving the plants to grow very fast, and, unless you have mastered the art of getting an optimum amount of CO2 available to the plants, they will be limited by the lack of adequate CO2. That isn't good, because that opens the door to algae infestations.

The EI dosing table is designed to maintain the fertilizers all at non-limiting amounts even for high light tanks. That means you might not need to increase that dosing at all, but even if you double the dosages no harm is likely to result. Resetting the tank every week with 50% or bigger water changes will take care of that potential problem.

Is there an aquatic plant club close to where you live? If so, they may have a PAR meter you could borrow if you join the group. If they don't have one, you can join and urge them to buy one. The cost is high for one person to justify, since we rarely need to make light intensity measurements, but when that cost is shared by plant group members, it is very reasonable. With a PAR meter you can tell just how much light you do have, and adjust the height of the fixtures to get the amount of light you want.
 

aquabillpers

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Jan 24, 2005
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If you have a much more reasonably priced lux meter, a reading of 2000 to 2500 is more than adequate to grow most plants. Note that the reading must be taken at the point where the plants get the light - at the substrate level for carpet plants and higher for others.

If you should want to convert metal halide lux to PAR for some reason, multiply the lux reading by .02. Here's a link: Units of PAR

Bill
 

mannwhite

Junior Poster
Feb 17, 2009
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thanks a lot guys for your replies. What I'm gonna do for now is try some KH4 water in my CO2 drop checker and see what my real value is and I'll see from there. Currently its colour is light green and my KH is 4.5-5 but since I'm using my aquarium water in my drop checker there's no telling what may or may not be affecting the reading.