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251 Posts
Discussion Starter · #1 ·
Last week I reduced the temperature in my tanks, and the plants are growing better now, I think. I had all my heaters set too high. Since it's summer and we try not to use the AC more than we have to, I pulled the heater out of several tanks. I used the temperature table in Christel Kasselmann's book as a guide to optimal temperature. I looked up the fishes' temperature range online as well, but always erred on the side of the plants.

265 Posts
Okay, I'm not much of a scientist, but here is my thought. Lower temperatures retain oxygen better. At higher temperatures, you need more artificial means of introducing oxygen, such as powerhead current or whatever. That water movement does introduce oxygen, but it also tends to release CO2. So, if you can lower the temp and reduce the water movement a little, you can retain the CO2 and the oxygen and get better plant and fish growth.

Could be wrong, but that's my story and I'm stickin' too it. (for now, lol)

251 Posts
Discussion Starter · #4 ·
Deets!?! Okay, you asked for it.

These three tanks are downstairs and we are only running the AC upstairs so tank temperature fluctuates more with the weather. It's been hot this week, in the mid to upper 90s. Note that "am" means before the lights come on at 10:00 am, and ideal temps are based mostly on the plants.

38-gal "South American and/or high light stuff" Ideal Temp 77 - 78.8 F

Echinodorus amazonicus?, E. bolivianus, Lobelia cardinalis 'Small Form'?, E. 'Rubin', Ludwigia repens x. "Palustris", Bacopa sp. 'colorata', Hemianthus micranthemoides, Hydrocotyle leucocephala, Potomageton gayii, Heteranthera zosterifolia, Phyllanthus fluitans, Riccia fluitans, Riccia sp. 'Dwarf', Hottonia palustris, Pogostemon helferi, Glossostigma elatinoides

5/26 pm 81.4 F removed heater
5/27 am 80 F
5/28 am 77.8 F
5/29 am 78 F
5/30 am 80 F
5/31 am 78.3 F
6/1 am 78.3 F
6/1 pm after wc 79.5 F
6/2 pm 79 F
6/3 am 79 F
6/5 am 79.5 F

18-gal "Southeast Asian" Ideal Temp 75 - 77 F
Cryptocoryne beckettii, C. crispatula var. balansae, C. wendtii 'brown', Microsorum pteropus, Bolbitis heudelotii, Taxiphyllum alternans, Blyxa japonica, Marsilea quadrifolia

Light is broken -- window and bedside lamp light only.
5/26 pm 78.9 F lowered temperature
5/28 am 76 F
5/29 am 77 F added new lamp -- 96 W wow!
5/29 +2 78 F
5/29 +10 82 F removed heater
5/30 am 80 F
5/31 am 80 put the legs back on the fixture to raise lamp 4 in.
6/1 am 78
6/1 pm after wc 80
6/2 am 80
6/3 am 78
6/5 am 79

1-gal "Nano" Ideal Temp 75 - 82 F

Hemianthus callitrichoides, Taxiphyllum sp. (Flame moss)

No heater -- heating pad under tank is off.
5/26 pm 76.3 F
5/27 am 75 F
5/28 am 73.4 F turned on heat 2 hours
5/29 am 74.4 F
6/1 am 74.3 F turned on heat
6/1 pm after wc 76.4 F turned off heat
6/2 am 73.7 F turned on heat and forgot to turn it off
6/3 am 80 F whoops turned off heat. must find extra timer.
6/4 wc
6/4 pm turned on heat before bed
6/5 am 80 F turned off heat
heating pad causes way too much temperature fluctuation.

These tanks are upstairs where there is AC.

10-gal "Guppy Tank A" Ideal Temp 75 - 77 F

Hygrophila difformis, Rotala rotundifolia, Bacopa caroliniana, Cryptocoryne wendtii

5/26 pm 77.7 F unplugged heater because I can't figure out how to turn the stupid thing down
5/27 am 76 F
5/28 am 75.6 F turned on heat 2 hours
5/29 am 76.1 F
6/2 am 75 F
6/5 am 75 F

10-gal "Guppy Tank B" Ideal Temp 75 - 77 F

Hygrophila difformis, Cryptocoryne wendtii, Hydrocotyle leucocephala, Taxiphyllum barbieri

5/26 pm 78.8 F turned down heater
5/27 am 77.5 F
5/28 am 75.3 F
5/29 am 75.4 F
6/2 am 74.8 F
6/5 am 74 F

265 Posts
Just after I lowered my tank temp, I noticed that two rasboras have a couple of ich spots. Sheesh. So far, the plants are faring very well and the ich is slowly retreating. Even the Macrandra is doing okay so far.

Premium Member
5,865 Posts
I'm with Luis, running my tanks ever so slightly on the high side of the mid 70s. I find that anything close to 80 or above is too hot. On the flip side, I tried running my tanks heaterless this past winter and they got down to 65 degrees and nothing was growing much at all.
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