Tropical Fish Forum

Tropical Fish Keeping Help and Advice => New Fishkeepers => Topic started by: TopCookie on May 15, 2018, 10:01:29 AM

Title: Tank Lights Photoperiod
Post by: TopCookie on May 15, 2018, 10:01:29 AM
Tricky question this one and hoping you guys might be able to offer some guidance...

Question is:  when trying to determine how long to have tank lights on per day, how much allowance should be made for natural daylight...?  To be clear; I do mean daylight and not direct sunlight... 

The room my tank is in is roughly west facing (more like west south west) and gets quite a lot of natural light in there...  Currently, I have my lights on for 7.5 hours per day, on a timer, but can't help wondering if this might actually be too long when considering that the room itself is fairly bright anyway...?
Title: Re: Tank Lights Photoperiod
Post by: Matt on May 15, 2018, 08:46:33 PM
I don't think there really is a way to properly calculate this. Even with a PAR meter it's impossible to tell the lighting need for your specific plants, the amount of nutrients dosed, carbon availability, temperature.... etc. There are just too many factors I'm afraid.

One thing I can say is that after approx 6-7 hours I believe the co2 levels in a tank are effectively depleted (though I can't remember where I've got this number from...) but nevertheless a good way to approach lighting is to have a siesta period in the middle of the day to allow co2 levels to increase again by limiting photosynthesis for this period which uses co2 and allow the respiration of the fish to add co2 to the tank. 
Title: Re: Tank Lights Photoperiod
Post by: TopCookie on May 15, 2018, 08:54:01 PM
Thanks Matt...  :)

The timer on my tank is a one shot sorta deal, as in once on and once off in a 24hr period...  Kinda makes the siesta plan a bit tricky (and I don't trust myself, lol)... 

I am wondering though if 7.5 hours is just a fraction more than needed and it sounds like it could well be...  Perhaps a good plan would be to slowly work it down to seven hours...?
Title: Re: Tank Lights Photoperiod
Post by: Matt on May 15, 2018, 09:58:06 PM
I would just mke the change for the sake of half an hour... that's one fifteenth change... so nothing to worry about.

There are guides online which will associate certain types of algae to having too much light... though I'm not sure how accurate they are, it would be interesting to see if they fit with your thoughts... Try http://www.tropicalfishsite.com/types-of-algae-growth-found-in-the-home-aquarium/ (http://www.tropicalfishsite.com/types-of-algae-growth-found-in-the-home-aquarium/)
Title: Re: Tank Lights Photoperiod
Post by: TopCookie on May 17, 2018, 11:13:02 AM
Split the difference in the end...  reduced by 15 mins and will do the same next week...  :)

Hard to say which algae it is precisely...  It is very fine, like hair algae, but not as prolific...  Looks more like the Staghorn, but not as chunky...  Similar colour to BBA, but entirely different shape etc... 

Am hoping that having gone back to using liquid carbon at the moment - which I can't tell you how reluctantly that decision was taken - that this, combined with the shortened/shortening photoperiod, will combat the algae even more...  The theory from day one of this battle was to get the plants out-competing the algae and there has also been some brutal trimming away of the worst affected leaves...  Once the inhabitants of the tank have acclimated to the use of liquid carbon, I'll slowly increase the dose to nearer recommended levels too...