Growing Aquatic Plants in the Aquarium pt 2

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Dr Mike Statham

cont. from pt 1.



Why is algae such a bane in planted tanks? The answer is simple, in trying to provide the right environment for higher aquatic plant growth you are also providing a perfect environment for some form of algal growth and if your plants aren't using all the resources then algae will use whatever is left over.

There are countless species of algae (even some which live in symbiosis with bacteria and can live in the weirdest and most extreme environments on Earth). There is always a species adapted to live in any aquatic environment you can provide, they grow incredibly fast, and their spores are everywhere and virtually indestructable. In the past people used to try all kinds of methods to get rid of algae spores, sterilising plants, tanks and equipment, and yet still algae would somehow get introduced. The fact is that algal spores are too small to see with the naked eye, can lie dormant for many years, and can be carried anywhere in the world by the slightest breeze. There are probably millions of them on your keyboard at this second.

Okay, so it's impossible to prevent algae getting in to your tank (don't even try), and it's impossible to prevent it from growing, but that doesn't mean you can't control the stuff so that it is kept in check and is all but invisible, and the best form of control is competition, competition from higher forms of plants - the ones you want growing in your tank!  

To out compete algae, plants must have sufficient: light, nutrition and CO2 (see part 1 of this guide) and must be kept in the right water conditions, e.g. hardness, pH. Once again knowing the requirements of your plants is very important here.

Some aquatic plants grow much faster than others. For example, Cabomba sp. are fast growing plants that can grow several inches a day, whilst Anubias are slow growing plants that might put out a new leaf, or two, a month. It must be noted that Cabombas are also much more demanding on growing conditions than  Anubias which are easy to grow in comparison, as Cabombas need more: light, nutrition AND CO2 due to their higher metabolism.

When you start out with growing plants in an empty tank, it pays to start with a lot of quick growing species, especially if the tank is newly set up. If planted properly, in sufficient quantities, and supplied with sufficient light, nutrition and CO2 (you don't normally need to add any of this - see Pt 1 of this guide), then these plants will quickly use up all the excess nutrition and light that would otherwise be utilised by algae. You will still get some algae, especially until the chemistry of the water in a new tank settles down, but hopefully not enough to be a problem and look ugly.

 Floating plants are quick growers and help prevent algae forming.

A lot of people add algae eating fish (e.g. 'Plecos') to try to get rid of algae. This works, to an extent, but a lot of the bigger 'Pleco' species grow very large, and most of them will quite happily eat your plants (or just tear them up) before they will even look at algae! 

For the 'algae eater' approach to work in a planted tank you must limit yourself to those species that stay relatively small and/or won't touch the leaves of plants. Good fish for this are Otocinclus sp. and Paraotocinclus sp. (e.g. Pitbull Plecs), but these aren't common in shops and don't adapt well to hard water. Otocinclus are the cheaper fish and more commonly available, but they should be kept in shoals as they prefer the company of their own kind. I have collected wild Otocinclus in great numbers amongst floating meadows of Water Hyacinth in Peru and they seem to prefer living amongst aquatic weeds in nature. These fish will often be seen hanging around on plant leaves in small groups and do a great job of cleaning algae off without damaging even fragile leaves. They are not easy to breed in captivity and are mostly (all?) wild caught, but they can live for well over 10 years in good conditions. Once again though I will repeat these fish do not like hardwater and don't generally survive for long in it, if you have hardwater look for other alternatives!

There are actually some much better options than fish for controlling algae which are available.

One of the easiest are snails, which you normally get for free with aquatic plants anyway! The small species of aquatic snails you will usually get as spawn on plants are deliberately introduced to nursery ponds for the specific purposes of controlling algae and turning over the substrate.          

Some common types of snails you might well find are:

Ramshorn Snails; these snails have attractive spiral 'Ram's horn' shells, and can be brown, speckled, or even bright red. These are good algae controllers, don't usually eat live plants and are attractive looking.

Paper Snails; these snails look a bit like 'Pond Snails' (those are not usually suited to tropical tanks by the way), but are smaller and have almost transparent shells. Another attractive species and a good algae eater.  

Malaysian Livebearing Snails (aka Malaysian Trumpet Snails or MTS); the shells of these snails look like long ice cream cones and they can grow quite large, often seen first thing after 'lights on' all over the front glass of a tank. These snails are prolific breeders and can become a pest, but this is outweighed by their benefit in turning over the substrate and getting nutrients down to the plants roots.

You can also buy so called 'Apple Snails'. These can grow huge (hence the name) and often become popular pets in their own right. They are great algae controllers and won't usually touch live plants. In the aquarium two, or more, will often breed laying big egg cases just above the water line on the glass. They are good for fry tanks as their waste promotes infusoria which fsh fry feed on. If they start to run out of algae feed them on boiled lettuce, cucumber etc...

Some fish will eat snails, Puffers and Loaches being the greediest. Puffers have beaks that can crush any snail shell, but loaches won't generally eat anything too big for them to tackle.

As an alternative to snails and fish you can also buy algae eating shrimps. The most popular (and cheapest) of these are so called 'Yamato', or 'Amano' shrimps. Takashi Amano is a very talented Japanese aquatic gardener who first made these shrimps popular. They are small, harmless to fish, and very good at eating algae, especially the 'hair algae' that many fish won't touch. Unfortunately they are hard to breed, requiring brackish water, and being tiny are eaten by most large fish. Some other species of algae eating shrimp are available now many are quite colourful, and some of these are easy to breed in the aquarium. Some are very expensive and great care must be taken when buying 'shrimps' that they are true algae eaters, and are not going to attack your fish!  

Finally, consider carefully before adding any form of chemical algae control to a planted tank, despite what it says on the bottle it will usually damage your plants (it couldn't kill algae otherwise), it won't kill algal spores, and it will not prevent algae from returning and re-establishing itself very quickly. 

How to Propagate and Plant Aquatic Plants

There is no great secret to aquatic gardening, it is very similar to growing plants in the house or garden really, and yet even many long term fishkeepers and shops get it consistently wrong!

A floating plant collection.

Firstly, lead weights have to be mentioned. These are a really, really bad idea. If they were useful aquatic plants would have evolved lead boots! They have one purpose only: to display the plants nicely in the shop and make you buy them.

Why are they so bad? Well, to start with putting them on to bunches of plants damages shoots and stalks, you have to squeeze them tight to get them to stay on and that crushes the plant tissues and kills the stems and leaves right at the base. Okay, nowadays most people use foam inside the lead to protect the stalks, but you still have to squeeze them tight causing irrepairable harm and promoting rot. Secondly, in the longer term they prevent plants from growing and spreading naturally, strangling a plant in this way will probably damage any new growth and cause rot that may well spread and kill off the entire plant, or large parts of it.

When you buy plants, whether crown plants, or cuttings, it is tempting to use lead weights to keep them down as they have a tendency to float until properly rooted. Bear in mind that using a lead weight in this way is not only likely to damage the plant, but may also prevent it from ever rooting at all! A better option is to use rounded stones, pebbles, or bogwood placed NEAR the plant as a temporary weight until the plant is established after a couple of weeks.

 A collection of cuttings and crown plants.

Potted plants are often available, these cost more than loose cuttings, plants, and weighted bunches, but are often well established plants when you buy them, so are worth the extra money. Also with particularly small and fragile plants this is the best way to transport them. But, the pots they come in must be removed, so that the plant can be planted in the substrate, or over time the pot will have much the same effect as a lead weight. Also, bear in mind that potted plants are grown in fibre wool (aka rock wool or glass fibre), this is fine when the plants are being grown hydroponically and drip fed nutrients, but it is not suitable for growing plants in the aquarium. The fibre wool must be carefully and gently removed from potted plants, causing as little damage to the roots as possible, in the case of particularly tiny plants trimming small pieces of rockwool off with a few rooted plants in it and planting those is the best approach.

When you get some new plants, the first thing to do is to soak them in a bucket of water or give them a good rinse under the tap to refresh them and wash off any chemical treatments. Then you will need to sort them and trim them. It is a good idea to have somewhere you can lay them out for a while without them drying out. An old newspaper laid out on the draining board and dampened is perfect.

To trim them examine each stem or plant and with a sharp pair of scissors remove any dead, dying, or broken leaves, stems and roots. Dead tissue will usually be brownish and soft. Handle the plants gently, but cut back hard, you want to remove all possible chance of rot setting in. New plants will often lose all their old leaves in a new tank anyway as they adjust to the new conditions and to being submerged, new roots will also sprout even if the plant is merely floated for a few days. Many aquatic plants can grow in and out of water, they are usually sold grown out of water as they travel better that way (stronger leaves and stems) and adapt better to your local water conditions. This is why even if a plant appears to die within the first couple of weeks of being planted, don't disturb it other than to remove dead leaves and give it at least a month to get established and adapt before you throw it away. Many plants will grow a completely new set of leaves and roots given a chance.

You should aim to trim the healthy roots on any crown plants back by around a third (but leave enough to hold the plant down!). This light trimming of the roots encourages new growth and speeds up the establishment of plants in their new home.

It is usually easiest to plant when a tank is full, of water. Planting in empty tanks is easier, but filling them with water afterwards will nearly always play havoc with your planting and force you to start again!

To plant crown plants such as Echinodorus sp. (Sword Plant), Vallisneria sp., or Cryptocorynes dig a hole in the substrate big enough to take the roots without bending them. Put the plant in the middle of the hole and gently fill in over the roots. At the end gently tug the plant upwards to ensure the crown is just above the substrate and the tops of the roots are just showing. Burying the crown usually makes plants rot and die.

Cuttings of stem plants should have the very end trimmed off with sharp scissors before they are planted as it will often be starting to rot. Strip leaves off the bottom couple of inches (5cm) of the stem, poke a narrow hole in the substrate with a stick, or your finger, and plant the cutting as deep as you need to, so that it stays anchored down. Space cuttings a good 2 inches (5cm) apart.

Bulbs are easy to plant. Many simply rest on the bottom with any roots pointing downwards and leaves upwards. Crinum bulbs look like spring onions, these should be half buried in the substrate with the sprouting end pointing upwards. In general bulbs should be planted just as deep as they need to be to prevent them floating. A stone of piece of bogwood resting on them can help to keep them down initially.

An aquatic bulb collection, they are usually easy to grow and dramatic.

Rooted plants can be planted in the substrate directly, or in pots filled with fertiliser and substrate which can then be concealed if desired. For big plants such as the Common Amazon Sword Plant Echinodorus bleheri it is necessary to have a depth of at least 2 inches (5cm) of substrate, idealy more. Many smaller plants with shallower roots are happy with less.

Terracotta pots make great planters for larger plants, and offer the roots some protection from digging fish.        

 Giant Vallis (Vallisneria americana) a very tough plant, growing in a large tank of Koi carp, the leaves are well over 24" (60cm) tall.

Some plants grow from rhizomes which need to be planted on bogwood or stones. Examples of these are: Anubias sp. and Java Fern Microsorum pteropus. These plants require special treatment. Don't trim off any damaged leaves or roots on these plants except as a last resort, and never trim living roots, they don't respond well to trimming. All of these plants are slow growing and require attaching to bogwood or stone by tying them carefully with black cotton (some people use plastic ties). These ties can only be removed once the roots are very well established and this usually requires at least six months of growth so it's best to tie them very well and use lots of cotton!

Aquatic mosses and similar plants don't require any planting at all and are mostly happy to float around in clumps, although if you want to get them attached to a piece of bogwood (or similar) and to stay in one place long enough to do so, then you must tie them down with black cotton too for a couple of weeks or wedge them in small cracks.

Finally floating plants don't require any special treatment, simply tip them in to the tank once it's full and tilt them the right way up if necessary. Most don't like any form of water movement and any leaves above the surface will get damaged by condensation, so it pays to lower the water surface a good 2" (50mm) below any condensation tray. Generally floating plants are fast growers and will require regular 'thinning out' to keep them in check.

  Salvinia natans is a beautiful and easy to grow floating plant.

Some Ideas on Aquascaping

It's beyond the scope of this guide to discuss how to lay out planted tanks in any detail, but I thought it might be useful to list a few simple ideas. At the end of the day exactly how you arrange and plant your tank is entirely your decision, it is your chance to create whatever kind of display you desire and to show off your artistic side!

Some thoughts:

  • Nature is a good source of inspiration, in reality many natural aquatic environments are devoid of plant life, or sparsely planted, but some are truly awesome underwater gardens, such as the seasonally flooded South American Pantanal.
  • 'Biotopes' using plants and fish from one part of the world often look very effective and natural.
  • Design the layout to suit the plants and fish you wish to keep, there is no point in trying to keep plants and fish that are incompatible, or to keep either of them in an inappropriate environment.

 Simple 'natural' schemes are often the most effective.

  • Keep it simple. Don't overcrowd the tank as this will limit light getting to the plants at the bottom, and try to limit your display to a few species that grow well for you. 
  • Plants usually look best planted in clumps of one species, but remember to allow room for cuttings and plants to grow to their full size. Thriving plants will often put out runners or shoots, eventually growing in to impressive thickets naturally.
  • Plant mostly easy, quick growing plants to start with. Later add some of the more specialist plants a few at a time, and be prepared for some species to grow better than others, not all species will be suited to the conditions in your tank.
  • Plant to allow for necessary maintainence. Use plants to conceal filters, heaters, etc..., but also allow space to get your hands in to prune and get to essential equipment now and again. 
  • Try to use plants to complement other features in the tank such as bogwood, rocks, or just open spaces.
  • Don't plant too symetrically, nothing looks more unnatural and 'fake'. If you struggle with this concept look into the 'Golden Triangle Rule' used by classical painters for inspiration.
  • Don't be afraid to experiment and break any rules you want!  

 Cherry Barb male amongst Nymphaea and Aponogeton sp.

*Copyright Dr M.Statham Last Trading Post 2006

*Permission granted for customers to print and download copies for personal use in original format only

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