I Was Giong To Buy A Better Light.... But Now Qs

[silkiechicken]

So I was going to go buy :

http/www.aquariumguys.com/current-nova-e...eshwater30.html

For my 20 gallon Long tank that is about 30 inches wide, 12 inches tall and 12 inches deep. Currently it has a crappy all glass single strip 18W light with stock bulb over the top and is supporting some java fern and hornwort. Java fern alive but is growing so slow that I think it might be frozen in time, while the horn wort does grow but is kind of spindly. For some reason, with the change in season, the trees outside dropped all their leaves and the horn wort did too!!! GAH! And the temp in the tank NEVER changed!

But then... I read a thread here that said without added CO2, for a 20 or so gallon tank, you didn't want to be over about 1 WPG...

Why is this? Will I have a total algae overload or something due to lack of Co2?

Would getting that lamp for the tank be overkill and asking for problems? I have a timer set so the light is on for 5 hours in the morning and 6 hours in the evening.

Suggesetions? Should I get the light or no?

 

[SuperColey1]

The reason of my post on the other thread was due to the type of tube used.

T5 tubes are extremely efficient and coupled with reflectors can be as much as double the WPG rule. i.e. if the actual calculation is 1WPG then you would be somewhere around 2WPG on the WPG rule. 2WPG on the WPG rule is the border between using CO2 and not using CO2.

T8 is nowhere near as efficient and you can basically use the WPG rule as it is.

The reason is that light is the main driver of the photosynthesis. think of it being the engine. Generalising I know but a fast car will have a larger engine.

However a larger engine will require more fuel. The fuel in a planted system is CO2 and the macro/micro nutrients.

So in summary the more light you have the faster the plants grow but to grow at the speed the light is driving them to they then need more CO2 and more nutrient.

In a low light tank there might be enough CO2 naturally in the water and gaseous exchange at the water's surface to suffice for the slower plant growth. There may also be enough nutrient from the fish waste and excess food.

In a high light tank you need to inject more CO2 to suffice the faster plant growth. You also need to add more nutrient.

For none CO2 I would suggest a maximum of 1WPG T5HO/T5/PC or 1.5WPG T8.

On the other parts you need to try and 'join' the photoperiods. 2 seperate long photoperiods a day are no good for plants. Try to make it one long photoperiod of between 8 and 10 hours.

You are right on the algae assumption. If you put light in that drives the plants but do not supply the CO2 and dosing needed for them to fed then algae takes advantage of the situation. A tank with no defficiencies is a tank with minimal algae. A tank with loads of defficiencies is a tank with loads of algae.

AC

 

[silkiechick]

The reason I have the light divided is because I like to see the tank in the hour before work, and in the 5 hours or so after work and before bed. Would it be better to just have it on in the morning for two hours, then again for 8 hours at night? I was trying to keep total light under 12 hrs a day, and if they can "see" min of 4 hrs, figured a split was better so I could at least enjoy seeing the tank. Being in the dim Pacific NW, it's nice to wake up to light and come back to light... since you usually leave in the dark and come back in the dark while sitting around inside at work during the normal light hours of the day. In the 6 months this set up has been running, I've not come to an algae problem yet, with the exception of some blue green algae that came on the java fern but eventually just disappeared after being wiped off as well as I could. I have 4 otos that may help with the algae, in addition to 6 tetras, and like 5 guppies

I guess really, all I want is plants to survive in the tank and grow a little to show they are alive. I'm fine with the java fern not really growing, but would like to replace the horn wort with broad leaf stuff like a sword style plant. Thing is those plants say "high light" which I don't have with just under 1WPG, and I don't want to buy it to just have it die a week later. I haven't been able to find any other low light plants at the LFS, else I'd have bought them already. What should I do!!! I just want it to be green like the garden in the summer!!!

 

[SuperColey1]

A lot of people seem to say Swords are highlight plants but I have never had a problem with under low light apart fomr they grow too big and fast. Different for everybody though.

When people say that plants need 4-5 hours min for photosynthesis that doesn't mean they will do it twice a day. Maybe they do but if not that means they will utilise one spell for their photoperiod and then give up for the day leaving the other spell for algae.

I would just choose morning or night for the lights and watch in the dark at the other time!!! Planted can be quite regimented in the way you can and often HAVE to do things.

Maybe someone else can clear up if the plants will photosynthesise twice a day as I don't know that.

AC

 

[aaronnorth]

Maybe someone else can clear up if the plants will photosynthesise twice a day as I don't know that.

yes they can, as soon as they recieve light, they start to photosynthesize (or at least 'warm up' until they reach that 4hr minimum point)

 

[silkiechicken]

Taking a decent chunk of biology (although with emphasis in bioengineering for my first degree, and cell and molecular bio for my second), I've seen chloroplasts under a microscope start to photosynthesize within about 5 minutes of direct light and you can see the little guys flowing directionally around the vacuole and produce sugar soon after. My guess for the recommendation of a single longer photo period has to do with the maintenance of the circadian rhythm which is key to things such as flowering (reproduction) and seasonal plant response due to the hormonal changes caused by light levels. However, if not breeding plants or trying to get them to flower, I don't really understand why a 12 hr cycle would be bad to the plants vs a 24 hour cycle where I just want them to stay green and grow since they would still be able to make sugars and store them for the same net periods of time. Then again, growing things in an aquarium is like trying to grow field crops in pots in you're basement. Can be done, just a heck of a lot harder.

If someone can give a good explanation on why there is a recommended continuous photo period for reasons other than reproduction, that would be awesome. About 90% of the research I see is in mammalian systems or plant flowering with respect to reproduction. Shows where humans like to spend their time focusing on. LOL

Maybe I will try a sword. Thanks for all the help! These aquariums are like 100x harder than field crops and chickens. Whew!