HQI lighting... Duration and intensity relationship.

[Iain Sutherland]

So the new tank set up taking shape im starting to plan lighting periods etc. Being as this is my first time with Halide lighting i'm fairly unsure.

Spec:
300ltr opti white 90x45x75
Pressurised co2 through Rhinox 5000 ceramic diffuser
1 x 150w HQI
2 x 24w giesemann powerchrome midday
Light will be 45-55cm from surface to accomadate emmersed growth.
EI ferts

Obviously while the tank is new lighting will be suspended higher and for shorter periods-
start with 2 x T5 for 2 hours before HQI comes on for 2 hours then 1 hour T5 after HQI off totaling 5 hrs.
My assumption is that the T5's will have very little par levels on a large tank and suspended so high :?

So the question... Will i be able to eventually get the lighting period to around 10 hours, 3 hours of T5 either side of HQI for 4 hours midday burst?
I fear I will be told that the plants will start to shut down long before the T5's go off and might cause algae issues??

Do plants have a 'set' period of time that they will uptake co2 and nutrients in any given day or is it dependant on the lighting cycle/ strength?

The reason i would like a longer period is i work shifts and regularly miss lights on all together which obviously has issues, especially new tank monitoring/ maintenance wise.

Im ready to be educated
Thanks

 

[foxfish]

Re: HQI lighting... watch Clive shoot me down!

150w over 300lt sounds good to me, I use my main light (70w MH over 220lt) for 6 hours but with a single 30w powerglow (blue tint) for 2 hours either side.
I don't keep the 30w on during the 6 hour growth period but I do have 10 hours of illumination.

 

[Iain Sutherland]

Re: HQI lighting... watch Clive shoot me down!

Thankyou foxfish, That sounds promising!
Any ideas if nutrient/co2 uptake is effected by duration or just light intensity?

 

[foxfish]

Re: HQI lighting... will Clive educate me?

Well in my instance I simply stick to the basic rules of gas on two hours before the growing light & standard calculations for EI dosing.
My 30w tube is just an effect in an attempt to replicate dawn & dusk but it offers enough light to enjoy the tank in a different light.
To be honest even 70w of metal halide is pretty bright in my lounge so it goes off at 7pm so we can enjoy the relative calm atmospheric & mellow hues of the 30w powerglow.
I find the fish are far more relaxed in the reduced light too.
I have used 6-7 hours of growing light for many years now, I am not in a competition & I hate algae.