Nit picky lighting question

jeff5614

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Aug 11, 2006
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I guess I should describe my setup first:
tank: 75 gallon
CO2: pressurized CO2 with DIY reactor, approx 30 ppm based on drop checker
filtration: fluval 304 and 404
lighting: 4x54 T5 HO
ferts: EI dosing recommendations for 75 gallon highlight with weekly WC
flora/fauna: heavily planted - java ferns, T belem, B japonica, D diandra, M fluviatilis, L aromatica, P stellatus, P yatabeanus, L brasiliensis
12 cardinal tetras, 5 black skirts, 3 serpaes, 3 von rios, 2 otos

My current lighting schedule is 2x54 from 11:00am - 9:00 pm and 4x54 from 12:00pm-6:00pm. Plant growth is pretty vigorous especially for the stem plants. I have some GDA that I usually wipe off the glass every other day before it becomes noticeable. I'd like to a little more viewing time with the lights on so I'm wanting to know your opinions on having 2x54's on from 9am-9pm and cutting the 4x54 period down to 4 or 5 hours per day. How might this affect growth and algae based on everyone's experience, etc? Thanks for taking the time to answer.
 

VaughnH

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I think you would do fine with 12 hours at 108 watts, and 4 hours at twice that. The potential problem I see is the GDA, which loves light. But, if you can continue to clean the glass every other day, you might get away with it.
 

raun

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Nov 7, 2007
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2x54 T5 HO with single light reflectors is already pushing into the "high light" category. Aqua Forest in San Francisco keeps some amazing tanks on just 2x54 T5 HOs.

I would suspect a rather small change in growth by reducing the light to your suggested levels. At 2x65 PC at 10 hours per day I'm still trimming at least once a week. As long as you're not running out of nutirents during the week I dont want to think about your maintenance schedule.... much too much work for me.

If you just want the extra lighting for show why not just turn them on from when you get home from work? Maybe 2x54 11am - 9pm and 4x54 6pm - 9pm, or some variation.
 

jeff5614

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Aug 11, 2006
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I do have quite a bit of trimming every week and I must admit that wiping the glass every other day is less than ideal. Slower growth woud be fine with me as long as the plants remain healthy. Do you all think the plants that I have would do well if I ran only 108w without any period of having all 4 bulbs on?

Raun, the extra lighting isn't for show, it's for growth. I think everything looks a bit washed out with all 4 bulbs on and prefer the look of it with only 2 bulbs.

I moved everything from a 55 around 3 weeks ago and I'm still trying to get a feel for the lighting in the 75. I used 2x54 in the 55 and that was more than enough light but I was concerned it might not be enough in a 75 so that's why I'm running with all 4 bulbs for part of the day.
 

jeff5614

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Aug 11, 2006
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I've looked at the pics of their tanks before and they're very well done. I hope mine looks as nice one day.
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After doing some more reading, the GDA thread in the Algae forum was very interesting regarding lighting, I've decided to stick with running 2x54's for 10 hours with a late afternoon burst of the additional 2x54's for 3 hours and see how that goes.

Raun, you mentioned my fert levels so I decided I'd just check my nitrates. This is the first time I've bothered in well over and year with a kit that I did calibrate at that time. I dose macros on Sat, Mon and Wed and that includes 3/4 tsp of KNO3 which ,based on a water volume of 65 gallons, is approx 9.7ppm. My nitrate read between 5 and 10 which surprised me since I thought I was probably dosing a bit heavy.
 

Tom Barr

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Jan 23, 2005
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Try 2x 54 W for 5 hours, then switch the other pair for 5 hours.

If you run a UV and micron filter, (Eg a magnum HOT+15W UV), and clean often, you should be able to get rid of GDA.

I've done this 3x now and it's pretty easy, with PC's, I find that high light really promotes GDA, but MH's do not.

Weird.

Regards,
Tom Barr
 

jeff5614

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Aug 11, 2006
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I do have a 25 watt UV and and I'll give the lighting schedule a try. Thanks, Tom.
 

jeff5614

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Well I decided to try running only 2x54 for the entire lighting period and I'm actually liking it. For the first time I can remember all I've had to prune this week was the P. yatabeanus. Everything else is still growing, just more slowly. GDA is still there but not as much.