# [Wet Thumb Forum]-Plants in coldwater low-tech aquariums.



## Miss Fishy (May 13, 2006)

My four aquariums are coldwater tanks, with a temperature range of 15°C - 26°C. I grow the same plants in them as I do outside in my ponds (temperature range 8°C - 38°C). In the ponds during summer you can almost see everything growing, and in the colder months the "tropicals" go through a dormant period, while the coldwater species slow down.

I mainly grow stem plants (including _Rotala, Myriophyllum_ and _Ludwigia _species, _Didiplis diandra, Hemianthus micranthemoides_), floating and rootless plants (_Chara, Nitella_, and _Utricularia _species, _Riccia fluitans, Ceratophyllum demersum, Lemna minor, Ricciocarpus natans_) and "carpets" (_ Marsilea and Lilaeopsis_ species, _Eleocharis acicularis, Glossostigma elatinoides_), as well as _Vallisnaria spiralis _and _V. gigantea_.

It's early winter here, and my tanks are at 15°C - 18°C. At the moment, _Hygrophila difformis _takes about four weeks to reach the surface of a 45cm high tank after being cut back to the gravel, and Duckweed takes three weeks to cover the surface of the same tank (90cm x 35cm).

What is an acceptable growth rate at these temperatures? How fast do these kinds of plants actually grow in a low-tech tank? There isn't a skerrick of algae anywhere, so I assume everything is fine.

From Alex.


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## hitty (Apr 15, 2005)

you really manage to grow rotala outdoors in melbourne??!!!

you'll have to give more details! 


i'm another melbournite.. and i never thought it was possible to grow anything more than duckweed outdoors during winter!


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## Miss Fishy (May 13, 2006)

Dear hitty,

Here are a lot more details!

As well as the plants I mentioned above, I also have Java Moss, _Rotala occultiflora_ (an Australian native species), and _Hydrocotyle _ growing outside year round. _Rotala rotundifolia_ grows particularly well emersed, and has lovely little pink flowers that make good cut flowers.

My ponds are in an old bath, a plastic wading pool, and a large collection of buckets, plastic storage containers and saucepans! All have topsoil and soft water (rain water and tap water with no additions). Most have a build up of dead leaves (plum, oak and ash) and mulm and an assortment of water creatures. Being small, they all have a high water turnover due to evaporation and overflowing during rain. Only the old bath has fish (two Goldfish). The only maintenance I do is refilling, feeding with fishfood and pruning.

One of my favourite ponds is a concrete plant urn with the drainage hole blocked that sits near the back door. It grows Java Moss, emergent _Rotala rotundifolia, Myriophyllum propinquum_ and _M. crispatum_. It only holds about two litres, but it looks really lovely with Rotala trailing down the sides. It did have some tiny water beetles in it, but it dried out one hot day and sadly they perished.

People have told me many times you can't grow "tropical" plants outside here, but as you can see, they are quite wrong! You should try these plants outside. I'm sure you won't be disappointed.

From Alex.


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## Phil Edwards (Jan 22, 2004)

Miss Fishy,

Acceptable growth is in the eye of the beholder. I would certainly call what you get acceptable, even respectable, growth. Personally, with Natural tanks, my philosophy is, if the plants aren't dying and the fish are happy then it's successful.


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## Miss Fishy (May 13, 2006)

Dear Phil, 

Thanks for replying. I was pretty sure everything was fine as the animals are thriving and there's no algae, but it's nice to be sure. My tanks with soil have only been running for four months so I only have my pond experience to go on. Since I've never noted at what temperatures things start to slow down in them I couldn't be sure that's what was happening in the tanks. 

Now I will enjoy the break from frequent pruning. During the summer, I had to prune the stem plants severely every two weeks or else I couldn't see into any of the tanks! 

I'm still waiting for some species to start out-competing others. I've still got 18 different species in one tank after four months. Aaargh! I like the look of tanks with masses of only a few kinds of plants, but I'm reluctant to take some species out in case I pick the wrong ones. If it goes the same way as my old bath pond, I'll just have to choose. Last time I checked I was surprised to find there were more than 20 species growing in there, and the pond is 11 years old. The upside is that when I want to start a new tank I don't have to buy many new species to get a good variety! 

From Alex.


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