I started digging a bit and got to some interesting info on the monsoon and the climate in Indonesia in general.
I used mainly Polish sites, but nevertheless I’ll give them for refernce:
http://en.wikipedia.org/wiki/Wet_season
http://www.transazja.pl/pl24/dane_klimatyczne/id/Indonesia/Jakarta/temperatura,opady
http://pl.allmetsat.com/klimat/singapur.php?code=48698
and info about Thailand for comparison:
http://pl.allmetsat.com/klimat/azja.php?code=48456
http://www.tajlandiaprzewodnik.pl/pogoda
What stikes me first is the fact, that there os actually only one monsoon season in Indonesia, while Thailand has two precipitation spikes. Since we are interested in Indonesia much more than in Thailand, I will drop the topic of the latter.
What we see next. The avarege temperature of the air is, more or less, constant and equals 27-28 degrees Celcius. But the interesting fact is that the amplitude of temperature varies greatly througout the year, with the smallest amplitude during the wet season in January, (33 max, 22 min), followed by moderate differnces till June, when the difference rises (35 max, 21 min) to reach the biggest difference in October (39 max, 16 min).
As to the rain. Having comparede the differences on the Borneo and in Singapure I can say, that the month with the heaviest rainfall is always January, and the most dry month is the June and/or July.
Here I’d like to state a thesis. Although the primary trigger is most probably the shortage of dissolved material, followed by the stabilisation of temperature and the land getting less sunligh.
I think that it is safe to assume, that water temperature measurments are taken during the daylight, so the recorded temperature is probably the peak temperature or maybe 1 degree Celcius lower. Now here’s the temperature chart for Jakarta:
http://www.panstwaswiata.pl/indonezja/pogoda/
The temperature varies from 3 to 5 degrees between night and day. Now let’s compare it to the annual chart, which in fact shows us, that the difference between avarege max and min temperature equals 4 degrees. This made me think. If it is so with this month, it should be probably the same with others. So I checked some meteograms, and charts, and found notes about weather on Bali in October
The difference is visible. 31 to 23 makes an 8 degree change. Usually, the recomended difference between night and day temperatures are between 2-3 degrees Celcius.
With that in mind I think, that simulating the change could effect in less spawns but of a grater calliber, with more eggs and therefore fishes. I’am not sure of it of course, but I intend to simulate the difference with a heat controller allowing to set day and night temperatures.
I think, that goal would be to make changes during the year: (Day/Night)
24/22 December, January
24/21 February, March
25/20 April, June, July, August
24/21 September, November
Accompanied with smaller water changes in summer and more frequent in winter.
The post might be a little chaotic, but the general idea should be visible. Most of my fish are young (about a year or so), so there is some time till the first spawning, but it might be interesting too see if the spawnings would start in the January 2014.
I’ll let You know how the experiment is going.