# High temperature



## niko (Jan 28, 2004)

I could not find any posts about how high temperature affects the plant growth so here it is:

Recently I added a killer T5HO light to an old established tank. The PAR reading from this fixture is huge and the color of the light is very beautiful. At the same time I added a larger filter and now there was both more biomedia and more flow. I increased the CO2 slightly anticipating fast growth of plants and algae.

A week after all the above changes nothing exciting had happened to the tank. The plants didn't grow at all. There was no pearling. There was some kind of encrusting algae that I had seen a few times in other tanks - very dark green, almost black. Looked like a very thin layer on plant leaves. Impossible to remove.

The heater had gone bad. It was an Ebo Jagger heater, only 2 or 3 years old. The temperature was 90F! I looked for info on high temp affecting the plant growth but as I said above - I could not find any.

One day after lowering the temp to 79F the tank was pearling heavily. One of the Anubias had sprouted a new leaf.

I had heard that ADA manipulates the processes in newly established tanks using lower temperature. But maybe you can do it with high temperature too. Except that from what I have seen in the past at 88F the Amano shrimp die.


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## Yo-han (Oct 15, 2010)

My tank was 90F for two weeks last summer, I didn't noticed any differences. Everything grow on, no algae, no deads etc. I think if it is not for too long and not a very sudden change (like it was probably in your case) it is no problem for a few days.

Even my unheated tank with Sewellia lineolata and Tanichthys micagemmae didn't suffered from it. The tanichthys even spawned.


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## JeffyFunk (Apr 6, 2006)

The main issue w/ temperature is that it affects the solubility of gases, the most important being CO2. At higher temperatures, the solubility of gases goes down and at lower temperatures the solubility of gases goes up. I'd wager that Amano uses this to his advantage by lowering the temperature initially to (1) increase CO2 for the plants to grow and establish themselves and (2) decrease the biological activity of the fish (if he has fish in the tank) since fish are cold blooded. 

For some plants, colder waters are required because of their demand for CO2. I've kept a few of my tanks unheated and cold(er), but not all the fish appreciated it...


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## BruceF (Aug 5, 2011)

Isn't the amount of disolved oxygen decreased at higher temps also? Around here the summer heat leads to algae explosions and fish deaths.


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## JeffyFunk (Apr 6, 2006)

BruceF said:


> Isn't the amount of disolved oxygen decreased at higher temps also? Around here the summer heat leads to algae explosions and fish deaths.


Yes, the amount of O2 dissolved would decease as well with increased temperature.

I always thought the algae explosions were due more to nutrient runoff from farms, however. This increased nutrient availability causes the algae to proliferate, resulting in an increased O2 use and causing the amount of dissolved O2 to plummet. This is what causes the fish deaths, supposedly.


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## Michael (Jul 20, 2010)

I grow a variety of aquarium plants in outdoor ponds during the summer here in Texas. I notice a slow-down in growth when we have extremely high daytime temperature coupled with high night time temperatures. Day time high temps with cooler nights do not affect growth.

Terrestrial plants show the same to a greater degree. The explanation is that the high night time temperatures keep the plant in heat stress 24/7. The plant never gets a break to recover from the damage. For terrestrial plants the definition of heat stress is a temperature at or above 86F. This sounds arbitrary, but is based on how temperature affects biochemical processes in plants. At 86F, essential processes slow or stop completely.

This may be different for aquatic plants, but my guess is that they would be more sensitive to constant high temperatures.


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