# Adjusting to new light - pc to mh



## IbnOzn (Mar 16, 2007)

I just changed the light over my 20 gallon from a 65 watt 6700k CF to a 70 watt 10000k hqi. Right away my tank started pearling like crazy where there was very little before and the few bubbles I had came late in the photoperiod. I'm keeping the same nutrient levels (25-30ppm NO3 & .5-1ppm PO4) and CO2 is at 30 ppm but I'm noticing thread algae starting to form. Would this indicate my 11hr photoperiod needs to be reduced? Maybe try 8 or 9hrs. for a while?


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## Ultimbow (Sep 10, 2005)

I put my hqi only for 8hrs and my other light 12hrs fixt my algea problem.


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## thefishmanlives (Feb 15, 2008)

you better shorten that 11 hour photo period asap. Id go down to at least 6 hours until algae subsides then work your way up. I use Excel until algae disappears and tank seems to have settled in.


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## BryceM (Nov 6, 2005)

Thread algae has recently been an issue in my MH/T-5 setup. I let the CO2 get low and within a week it was an absolute disaster. Now, more than a month later, it's finally starting to come under control again.

Very intense light is possible to deal with, but everything must be perfect all of the time. CO2 simply MUST be optimal - good concentration and good distribution througout the tank. Other ferts must also be kept strictly in line. Any deviation and things crash hard very quickly.

Most people who use MH in a planted tank only keep them going for 3-5 hours per day. You can use some other less-intense light for regular viewing for the balance of the day.


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## IbnOzn (Mar 16, 2007)

Thanks for the replies. I brought it down to 7.5 hours and have started dosing Excel.


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## Bunbuku (Feb 10, 2008)

I run my 150 watt MH for only 6 hrs a day, based on the ADA recommendations here http://www.adgshop.com/ProductDetails.asp?ProductCode=108%2D036&Show=ExtInfo

CO2 kicks @ 2 bbps 1 hr before lights on and off 30 min before lights out. I am not algae free, some is OK to feed the algae crew. There is some on glass near the substrate line and smattering on Blyxa but all in all its all seems to be in balance. I had been dosing with the ADA line but recently switched to Pfertz - in hopes that the Blyxa might get more red coloration.

(My 60-P algae crew - 8 Amano's, 3 Oto's, 4 adult tigers and a bunch of babies)


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## BryceM (Nov 6, 2005)

Red Blyxa is all about light (and iron).


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