What length photoperiod do you recommend?

[AquaticJim]

My tank is 4x2x2 and lit with 2 x 150watt metal halides.

Water temp is 28.5c

EI dosing is 4.5 teaspoons of KNO3, 1.5 teaspoons of KH2P04 in 140mils of distilled water and dosed at 20 mils per day and 10 mils of Seachem Flourish a day, Seachem Iron doses twice a week.

2 x 60% - 70% water changes a week.

Filtration and water movement is via 2 x Eheim 2217's

Co2 comes on at 10.00am and off at 10.00pm with a very high bubble count.

Lights come on a 1.00pm and go off at 11.00pm

So the photoperiod is 10 hours, I've notice Ambulia 'shutting up shop' after 9 hours and the entire tank pearling a site to behold.

I have noticed that my exposed inert gravel is starting to get some very dark green algae on it and also I am seeing some algae forming on my older chain sword leaves and also some very dark green algae forming on my driftwood.


Should I cut the photoperiod down? or is it something else that I am (or not) doing?

 

[Tom Barr]

I do 7 to about 10 max.
You might even be okay with 6 depending on how close the light is.

 

[AquaticJim]

Thanks Tom. I'll cut it down to 8 to start and see if that makes a difference with two hours less.

I may have to start my CO2 4 hours before 'lights on' though, because otherwise I don't think there'll be enough hours of CO2. Is that any concern??

 

[Tom Barr]

I'd only start 1 hour max before lights ON.

If you need more, somethings not right with the CO2 set up and it cannot possibly keep up with demand.

15-30 min is a better range, mine is about 5 min response time.

 

[AquaticJim]

Something is amiss then. I'm using a Dupla Reaktor 400 with a really high bubble rate -

http://www.youtube.com/watch?v=aolpnbx291A

It takes nearly 7-8 hours out of the 11 in total that the gas is on for changes to happen in the drop checker.

 

[nipat]

---

So the photoperiod is 10 hours, I've notice Ambulia 'shutting up shop' after 9 hours and the entire tank pearling a site to behold.

---

I would predict if you have reduced to 8 hrs for a while, they will adjust themselves to shut after 7 hrs.
This has happened to me. So I now have stopped taking the closing leaves as the sign.