# Temperature, light and algae - a tale of 2 tanks



## Molch (Nov 10, 2010)

I recently set up 2 new 20 gallon tanks by the Walstad method. In one of them, plants are growing prolifically and there's no trace of algae. In the other, plants do ok but not great; some feathery stems (Limnophila, Myriophyllum) have died, and I see some green fuzz algae in leaves.
Both have the same plant species: Limnphila, ceratopteris, shinnersia, rotala, java fern, riccia, wisteria, myriophyllum

The tanks differ according to light and temps, but have similar water values:
both have a pH of 7.5, 150 ppm KH and GH ca. 7-9, no ammonia or nitrite and ca. 5 or less ppm nitrate:

The "good" tank: my cold-water newt tank
57 F cold water
8 hr photoperiod
2 x 26 watt (each a 100-watt equivalent) compact daylight CFLs
Tank has bare bottom, but plants are planted in shallow bowls and trays w. 1 " potting soil and ½ to 1 " gravel/sand 
No filter
4 newts

The "not-so-good" tank:
74 F warm water
13 hrs photoperiod
2 x 20 watt T12 cool white tubes
1" potting soil under 1" gravel
Small internal filter w. sponge and charcoal
Ca. 15 1" fish

Help me work this out: is the difference due to temperature? Photoperiod/duration? I suspect it's the latter. If plant photosynthesis reduces CO2 by early afternoon, might one as well turn lights of then so algae can't gain an advantage? And might one just as well supply stronger light during a shorter period so plants can grow actively for a few hrs and then replenish CO2 while lights are out?

Please tell me what you know/think!


----------



## Molch (Nov 10, 2010)

well, I reduced the photoperiod in the warm water tank and inserted a siesta - approx. 4 hrs on, 3 off, 4 on.

In the cold tank, The Shinnersia has grown to such proportions that I will trim it soon. Egeria and myriophyllum are also growing nicely. The Ludwigia is growing more slowly but is healthy and red.

In the warm tank, Shinnersia grows, but looks thin and spindly, not lush and fat like in the cold tank.

In summary, NONE of these plants looks better in the warm tank. The best I could say is that some look about the same (Rotala rotundifolia, java fern)


----------



## joshvito (Apr 6, 2009)

I think temperature has a lot to do with plant health too.
I think colder water can hold more gases (e.g. CO2).


----------



## Molch (Nov 10, 2010)

but how much more? I've been googling for temperature-related CO2 tables, but no luck. I know cold water holds more O2 for sure.

Has anyone seen a table?


----------



## neilshieh (Jun 24, 2010)

and also your not so good tank uses cool white bulbs, they need to be daylight (6500k)


----------



## Sleepy Angel (Jan 13, 2011)

Try switching the lights between the two tanks and see what happens.


----------

