Lighting Requirements for 35 g planted tank

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bbrown

Aquarium Advice Regular
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Mar 11, 2005
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Alberta, Canada
I have a 35 g gallon community tank - 36 inches long - 18 high. It has recently been heavily planted (thanks to the Calgary Aquarium Society annual auction). Some of these plants require more light than I currently have (30 watt Aquaglow). I have ordered a power compact system which is approx. 96 watts. Will I be ok with this wattage without CO2?? If not, could you suggest an alternative light.
 
96watts over a 35gallon will require CO2, unless you love the look of algae covered plants.

Anytime you go over 1.5watts per gallon, CO2 becomes a good idea. Over 2.5wpg and...well, I can't imagine trying 2.5wpg without CO2.
 
How much light do I need then? Tank is planted with a variety of swords (some red flames), crypto wendtii, balansae and echinodoras osiyis, anubais, java fern. I do not think I am experienced enough to deal with CO2.
 
Malkore, you said

malkore said:
96watts over a 35gallon will require CO2, unless you love the look of algae covered plants.

Why is that?

And
malkore said:
Anytime you go over 1.5watts per gallon, CO2 becomes a good idea. Over 2.5wpg and...well, I can't imagine trying 2.5wpg without CO2.


Would you mind elaborating on this…

I have around 2.2 wpg and I get a good bit of algae on my plants.
 
When you hit a certain light level, the limiting nutrient becomes Carbon...coming from Carbon Dioxide gas. If the plants can't breath CO2, they can't consume nitrate and phosphate (the two macronutrients that are also responsible for algae blooms).
So without CO2 the plants get stunted, and you have all this extra 'food' available, so the algae takes advantage of this.

Plants also emit allelochemicals (i totally misspelled that) which inhibit algae growth. its my personal theory that stunted plants don't produce these chemicals...making algae blooms that much more likely.

When you add strong lighting to a tank, the plants will go nuts for a week, then they have no stored carbon left. Then algae shows up, and its an uphill fight to get rid of it. Adding consistent levels of CO2 kick the plants back into gear, and the algae will subside on its own, provided you have a proper ratio of nitrates to phosphates (10:1 is a common ratio, 15:1 also works), enough potassium (around 15-20ppm), and your trace ferts are good.
 
Thank you so much for taking the time to reply to my query. I would have spent $170 on 96 watts of light which would not have worked for me. I called the retailer and cancelled the order. I am going to try a fluorscent 40 watt bulb which the store said has 18,000 k. He said I should not need anymore than that. It is also considerably cheaper. I guess my plants will tell me how they are doing. Can Laterite be added to the substrate after the plants are planted?? Is it necessary. I do fertilize weekly (with my water change) with Seachem's Flourish. Thanks again,
 
I wouldn't recommend using any bulb over 10,000K for a planted tank. The PAR (photosynthetically active radiation) of bulbs rated over 10,000K is very low for most plants and they will not benefit much from it. Bulbs over 10,000K are most commonly used for saltwater reef tanks and are beneficial to SW corals and macroalgae but not to freshwater plants. I'm not saying it will kill your plants but it won't provide them with much of what they need as it is too much toward the blue end of the spectrum to grow plants. Look for bulbs rated between 5,000 - 10,000K and you should be just fine.
 
malkore said:
When you hit a certain light level, the limiting nutrient becomes Carbon...coming from Carbon Dioxide gas. If the plants can't breath CO2, they can't consume nitrate and phosphate (the two macronutrients that are also responsible for algae blooms).
So without CO2 the plants get stunted, and you have all this extra 'food' available, so the algae takes advantage of this.

Plants also emit allelochemicals (i totally misspelled that) which inhibit algae growth. its my personal theory that stunted plants don't produce these chemicals...making algae blooms that much more likely.

When you add strong lighting to a tank, the plants will go nuts for a week, then they have no stored carbon left. Then algae shows up, and its an uphill fight to get rid of it. Adding consistent levels of CO2 kick the plants back into gear, and the algae will subside on its own, provided you have a proper ratio of nitrates to phosphates (10:1 is a common ratio, 15:1 also works), enough potassium (around 15-20ppm), and your trace ferts are good.

Wow Kudos for you!,,, so that could explain why most of my plants are stuck at a plateau, I put them in they would grow and grow then just stop, then the algae would (black, and green) start to form on there leaves.

Thanks A whole bunch.
 
I'm at about 2.6watts/gallon on my tank. I only use Flourish excel 1-2x/week. I scrape off algae once a month. It doesn't get too bad. :) Maybe I'm just getting lucky so far.
 
aquazen said:
I'm at about 2.6watts/gallon on my tank. I only use Flourish excel 1-2x/week. I scrape off algae once a month. It doesn't get too bad. :) Maybe I'm just getting lucky so far.

The Flourish Excel is supplying your carbon for your plants.
 
I guess my point is you don't have to have a 'constant' source like a cylinder to prevent outbreaks of algae. I just recommend dosing at regular intervals. I have heard that you can overdose on Excel (not you, the fish of course), so use only as directed. I hear it's a good alternative for tanks 30 gallons and lower. I personally love the stuff. My plants all look pretty healthy. The cylinder is probably the best way to go since you can set it and go, but the initial set-up cost is what prevents me from using one. Besides, mine's only 10 gallons. :p
 
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