Aquarium Plants 1.01

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Fish Guru
Jan 26, 2008
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Perth, WA

Stress from tank lights coming on when the room is dark can be an issue. Fish don't have eyelids and don't tolerate going from complete dark to bright light (or vice versa) instantly.

In the morning open the curtains or turn the room light on at least 30 minutes (or more) before turning the tank light on. This will reduce the stress on the fish and they won't go from a dark tank to a bright tank instantly.

At night turn the room light on and then turn the tank light off. Wait at least 30 minutes (or more) before turning the room light out. This allows the fish to settle down for the night instead of going from a brightly lit tank to complete darkness instantly.

Try to have the lights on at the same time each day. Use a timer if possible.

If the light unit is programmable, have it on a low setting for the first 30-60 minutes and increase the brightness over time. Do the opposite in the evening and gradually reduce the light for the last 30-60 minutes before lights out.

If you don't have live plants in the tank, you only need the light on for a few hours in the evening so you can watch the fish. You might turn them on at 4 or 5pm and off at 9pm.

If you do have live plants in the tank, you can have the lights on for 8-16 hours a day but the fish and plants need 8 hours of darkness to rest. Most people with live plants in their aquarium will have the lights on for 8-12 hours a day.


Most aquarium plants like a bit of light and if you only have the light on for a couple of hours a day, they struggle. If the light doesn't have a high enough wattage or correct colour spectrum they also struggle. Try having the tank lights on for 10-12 hours a day.

If you get lots of green algae then reduce the light by an hour a day and monitor the algae over the next 2 weeks.
If you don't get any green algae on the glass then increase the lighting period by an hour and monitor it for a couple of weeks.
If you get a small amount of green algae then the lighting time is about right.

Some plants will close their leaves up when they have had sufficient light. Ambulia, Hygrophilas and a few others close their top set of leaves first, then the next set and so on down the stem. When you see this happening, wait an hour after the first few sets of leaves have closed up against the stem and then turn lights off.


Plants primarily use red and blue light, as well as a small amount of green light, and should have light that resembles sunlight (with or without UV light). Lights with an equal amount of red and blue light and a bit less green light are fine for aquarium plants. There are numerous light units and globes on the market and you simply get one that has a temperature rating of 6500K (K is for Kelvin). A 6500K globe (often referred to as a cool light) will produce a white light and is pretty close to sunlight, minus the UV light. A globe that has a lower Kelvin rating (say 4000K) will produce more red and yellow light with less blue light. A globe that has a Kelvin rating of 8000K will have lots of blue light but not much red light. So try to find a globe that is around 6500K.

If the light has a colour spectrum chart, see if it has equal or similar amounts of red and blue light on the chart. They usually have peaks (maximum levels) and you want the red and blue to be similar. They don't have to be exactly the same, just similar. If the blue has a peak that is double the red or vice versa, then avoid that light.

If you have a light unit that can have different coloured light, don't have just blue or just red light because this is not natural for the fish or plants. Just have equal parts red and blue so the colour is balanced and looks normal.


If you have two light units on the tank, put them on timers and have one come on first, then an hour later the second one can come on. It will be less stressful for the fish.

In the evening, turn the first light off and wait an hour, then have the second light go out.

If the lights have a low, medium and high intensity setting, have them on low in the morning, then increase it to medium after a couple of hours, and then high for the main part of the day. In the evening, reverse this and have the medium setting for a few hours, then low. Then turn the lights off.


Light is the key to plant growth. They need nutrients as well but the main factor is light. Without sufficient light, the plants won't grow. Aquarium plants originated from wild collected specimens that grew in full sun light. The plant farmers usually have them in full sun too. It's only when the plants are at a pet shop or put in the home aquarium that they are put under artificial lighting, which is significantly less intense than the sun light they got outside.

Some plants are grown in a laboratory (tissue cultured plants) but even these have lots more light than the average aquarium. Tissue cultured plants are grown in glass containers on wire racks and have multiple rows of light above each rack of plants. The amount of light the tissue cultured plants get is way more than a normal aquarium light but way less than sun light.

Light is reduced in water too and the deeper the water, the less light penetrates it. In an aquarium that is 18 inches high a normal LED plant light will usually produce enough light to get to the bottom of the tank. But if the tank is 2 or 3 foot high, then you need higher wattage lights to get enough light to the bottom of the tank. In the wild, most freshwater aquatic plants grow in water that is less than 10 feet deep, and usually the water is only 2-4 feet deep. When the water is more than 20 feet deep, the amount of red light getting through the deeper water is reduced and other wavelengths (colour spectrums) of light also get absorbed by deeper water. Blue light tends to penetrate the deepest water.


Some good plants to try include Ambulia, Hygrophila polysperma, H. ruba/ rubra, Elodia (during summer, but don't buy it in winter because it falls apart), Hydrilla, common Amazon sword plant, narrow or twisted/ spiral Vallis, Water Sprite (Ceratopteris thalictroides/ cornuta).

The Water Sprite normally floats on the surface but can also be planted in the substrate. The other plants should be planted in the gravel.

Ambulia, Hygrophila polysperma, Elodia/ Hydrilla and Vallis are tall plants that do well along the back. Rotala macranda is a medium/ tallish red plant that usually does well.

Hygrophila ruba/ rubra is a medium height plant that looks good on the sides of the tank.

Cryptocorynes are small/ medium plants that are taller than pygmy chain swords but shorter than H. rubra. They also come in a range of colours, mostly different shades of green, brown or purplish red. Crypts are not the easiest plant to grow but can do well if they are healthy to begin with and are not disturbed after planting in the tank.

Most Amazon sword plants can get pretty big and are usually kept in the middle of the tank as a show piece. There is an Ozelot sword plant that has brown spots on green leaves, and a red ruffle sword plant (name may vary depending on where you live) with deep red leaves.

There is a pygmy chain sword plant that is small and does well in the front of the tank.


We use to grow some plants (usually swords, Cryptocorynes, Aponogetons and water lilies) in 1 or 2 litre plastic icecream containers. You put an inch of gravel in the bottom of the container, then spread a thin layer of granulated garden fertiliser over the gravel. Put a 1/4inch (6mm) thick layer of red/ orange clay over the fertiliser. Dry the clay first and crush it into a powder. Then cover that with more gravel.

You put the plants in the gravel and as they grow, their roots hit the clay and fertiliser and they take off and go nuts. The clay stops the fertiliser leaching into the water.

You can smear silicon on the outside of the buckets and stick gravel or sand to them so it is less conspicuous. Or you can let algae grow on them and the containers turn green.


We did plants in pots for a couple of reasons.
1) I was working in an aquaculture facility and we grew and sold live plants to shops. Some of the shops wanted advanced plants in pots so we did that.

2) Plants like sword plants love nutrients and have big root systems so they needed more gravel and big pots. When given ideal conditions these plants would produce lots of runners with new plants on and we got more plants to sell.

3) Most of the tanks only had a thin layer of substrate that was nowhere near thick enough for plants to grow in so having them in pots allowed us to grow plants in tanks with minimal gravel in the tank.


Lots of plants are sold as aquarium plants and most are marsh plants that do really well when their roots are in water and the rest of the plant is above water. Some marsh plants will do well underwater too.

Hair grass is not a true aquatic plant, neither is Anubias. Reeds and rushes are not aquatic plants and will die if their leaves are kept underwater.

Some common marsh plants include Amazon sword plants, Cryptocorynes, Hygrophila sp, Rotala sp, Ludwigia sp, Bacopa sp. These plant do reasonably well underwater.

True aquatic plants include Ambulia, Cabomba, Hornwort, Elodia, Hydrilla and Vallis.

The main difference between marsh plants and true aquatic plants is the stem. True aquatics have a soft flexible stem with air bubbles in it. These bubbles help the plant float and remain buoyant in the water column.

Marsh plants have a rigid stem and these plants can remain standing upright when removed from water. Whereas true aquatic plants will fall over/ collapse when removed from water.


All plants, including aquatic plants need nutrients to grow and thrive. There are plenty of aquarium plant fertilisers on the market and most do the same thing. Some have nitrogen (N), phosphorus (P) and potassium (K) in and these are not normally needed in an aquarium. Aquatic plants get their nitrogen from the fish, fish food and waste in the water. Phosphorus in aquariums can encourage algae, and potassium isn't needed unless the plants are flowering and most true aquatic plants don't flower.

There are iron based aquarium plant fertilisers, and these will help most aquarium plants do well. Most iron based fertiliser is not just iron, it contains other nutrients as well, but they don't normally have nitrogen, phosphorus or potassium in and the main ingredient is iron. The liquid iron based aquarium plant fertilisers tend to be better than the tablet forms, although you can push the tablets under the roots of plants and that works well.

You use an iron (Fe) test kit to monitor iron levels and keep them at 1mg/l (1ppm).

I used Sera Florena liquid plant fertiliser but there are other brands too.

*NB* Do not overdose any plant fertiliser because you can poison the fish.

*NB* Do not use terrestrial plant fertiliser in an aquarium unless it is trapped in a way so it can't leach into the water. Terrestrial plant fertilisers contain ammonia and this can wipe out an aquarium very quickly.


There is no point adding carbon dioxide (CO2) to an aquarium until you have the lights and nutrients worked out. Even then you don't need CO2 unless the tank is completely full of fast growing true aquatic plants and only has a few small fish in or no fish in it.

There are no natural waterways anywhere around the world that have supplemental CO2 added to them to make aquatic plants grow. People add CO2 to aquariums to help some marsh/ terrestrial plants grow underwater. These plants should not be grown in aquariums and the fact they need to add CO2 (as well as huge amounts of fertiliser and light) just to keep them alive is a clear indication they shouldn't be kept underwater.

In an average aquarium, there is a constant source of carbon dioxide produced all day and night by the fish, and the bacteria in the gravel and filter. More CO2 gets into the aquarium from the air mixing with the water. And plants release small amounts of CO2 when resting. There is no real need to add CO2, either in a gas or liquid form to an aquarium unless it is devoid of fish. There is plenty of CO2 in the water in most aquariums.

Liquid CO2 boosters often contain Glutaraldehyde, which is a disinfectant used to clean and sterilise medical equipment. It is highly toxic to fish and other aquatic organisms and people have wiped out tanks by adding too much of it. These products should not be used for aquariums.

For aquarium plants to use supplemental CO2, they need lots of light and lots of nutrients. Unless they have the light and nutrients, they won't use a lot of CO2, so there's no point adding extra. To check if your plants are getting lots of light, see if any of them produce streams of tiny little bubbles from their leaves. This is called pearling and is the plant photosynthesising and producing tiny bubbles of oxygen. Algae also does this when given bright light and nutrients.


Some pet shops sell aquatic plant substrates that are meant to improve plant growth. Most don't do anything except add a lot of ammonia to the water and eventually they stop adding anything to the water and turn into a brown mud on the bottom. Since the majority of aquatic plants take in the nutrients they need via their leaves, having a plant substrate is not going to help them much. There are exceptions to this and laterite (red clay) can sometimes be added to the gravel to increase the iron level for the plants taking in nutrients via their roots. But for most plant tanks, all you need is sand or gravel on the bottom of the tank.

Most aquatic plants need at least 2 inches of substrate to grow in and some need 3-4 inches.
A lot of the above is good information, However, there are some points I would suggest are the opposite of what is actually the case. This is especially true in terms of the CO2 information.

The reason some tanks need added co2 is because the type and quantity of plants will use the available CO2 faster than surface agitation can supply it. I ran such a planted tank for about a decade. It used pressurized CO2. One of my favorite plants was Rotala macrandra. The source I most trust for excellent plant information is Tropica. Here is what the say about this plant:
Rotala macrandra ‘Japan’ is a magnificent aquarium plant, but unfortunately, it is very demanding. This variant is a little easier to grow and develops better coloration. It needs very good light to develop its beautiful red shades, just like CO2 addition and soft water are vital to ensure optimal growth.
Cut the longest stems 5-10 cm from the ground and replant them in the group.

Here is a picture of my Rotala mac. in my CO2 added high tech planted tank. (Yes, it is pearling.) I took the tank down some time ago because it required too much of my time to keep in shape. I am first and foremost a fish keeper who uses plants primarily to benefit them.


I still have 7 tanks with plants, but they are now all the easier lower light and CO2 demanding ones. However, I still add Excel and Tropica ferts weekly after water changes. I have been adding Excel to my planted tanks now for over 20 years. As far as I am concerned it does not harm fish when used properly. At my peak I was adding it to 13 planted tanks, I did not add it in the tank with the pressurized CO2.

I have been keeping clown loaches for over 20 years. My current biggest is almost 12 inches and been in my tanks for 20+ years. I lost my biggest one about 18 months back it was bigger and about 23 when it passed. The clowns have been in a planted tank with Excel added weekly the entire time I have had them. Their tankmates are redline barbs. A recent visitor commented that the oldest and largest was the biggest one he had ever seen. I get them at under two inches and they absolutely thrive in my planted tanks.

But consider this, please. Excel has now been around for a decent amount of time and many people have been using it. Do we actually think that if this was killing fish with any regularity there would not have been a hue and cry raised across the globe online? I have read a few people saying what Colin does about Excel. What I have never seen so for is any form of documentation that Excel killed a given fish.

And then what about folks who are using Excel weekly and go for many years without having a fish die in their tank? And even if one were dosing a harmful but not a lethal level, would it not stress the fish which weakens their immune system and makes them more likely to get sick or attacked by parasites. If Excel is so awful for fish, where is the pile of evidence?

There are many potentially harmful things in our tank water in concentrations that are minimal. At that level they may benefit the plants, the fish and the water parameters. But,. at elevated levels, they become toxic.

Too much CO2 can harm fish, so maybe we should remove CO2 from the water?
Too much food can rot and cause nasty results, should we stop feeding our fish?
Too much fertilizer can be toxic to both fish and plants, should we stop adding fertilizer to all planted tanks?

The answer is no we should not, what we should do is to add those and other things at the proper levels. Both too little or too much of things can produce bad results.

Also, "Some good plants to try include Ambulia, Hygrophila polysperma,"

Hygrophila polysperma​

East Indian hygrophila
Hygrophila is prohibited and therefore not recommended by UF/IFAS. Hydrophila is on the USDA Federal Noxious Weed List and the FDACS- Florida Prohibited Aquatic Plant List. The UF/IFAS Assessment lists hygrophila as prohibited, with high invasion risk. It is listed by FLEPPC as a Category l invasive species due to its ability to invade and displace native plant communities.
There may not be a pile of dead fish around the world from Glutaraldehyde but why deliberately add a poison to the aquarium when it's not necessary. Isn't it better to try and avoid adding unnecessary things to the water than possibly risk slowly poisoning the aquarium inhabitants?

Hygrophila polysperma might be an invasive weed in the US, it might not be in other countries and isn't in Australia. There are plants that are available in the US that are considered weeds here. If people have concerns about any of the plants listed, check with the local Department of Agriculture and see if the plants are considered weeds in your area.
What evidence do you have to support the idea that proper use of Excel slowly poisons fish? It seems to me that with all the people using Excel regularly over extended periods of time that the fishkeeping community would certainly have seen some sort of evidence that their fish have been slowly poisoned.

What are the symptoms/effects one should look for in their fish to indicate that the use of Excel in their tank is slowly poisoning anything.

1. Should fish swim abnormally at some point.
2. Should the growth of fish be slowed?
3. Should the fish become sterile and unable to breed? Or should they have deformed offspring?
4. Should the colors of a fish be affected in some way?
5. Will fish, at some point, behave in a way we might describe as crazy or way out of the ordinary?
6. Should the expected average lifespan of fish be shortened?

And even more importantly I wonder about this. In my over 23 years of keeping fish and having an assortment of planted tanks, I have talked to many fish keepers. I have been a member on many forums dating back to 2001. I have attended fish events and am a member in an aquarium club. In that time I have spoken to many individuals and read threads from them and have sat through presentations about "sick" fish and medications. This included parasites, and worms and even argulas. I have encountered ich and velvet, bacterial diseases, viral infections and even contaminants getting into tanks.

In all that time I have never asked nor have I ever heard anybody else ask a person needing help with some sort of health related issue in a tank if they add Excel. It seems to me if it were as nasty as described in this thread there would be a few savvy fish experts out there asking this question of anybody with a planted tank and sick fish.

I am not a planted tank site type of person. But I think both UKAPS and Tom Barr's site do not believe Excel is a slow poison that should not be used. They suggest using it for some planted tanks.

As far as I can tell the other ingredients in Excel are able to affect glutarahdehyde in a way that converts it to something not toxic to fish and able to be used by most plants in our tanks.

I add Excel because I see evidence that it benefits the plants and I see no evidence that it is harming the fish or inverts for that matter.

"Hygrophila polysperma might be an invasive weed in the US, it might not be in other countries and isn't in Australia."
As far as I can tell there are a fair number of American members here. So I felt it was a good idea that they know about Hygro poly.

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