Will hornwort's alleopathic chemicals affect growth in other plants?

[UnityLover]

^^^
If so, how much? Should I wait to add it until everything else is established?

 

[Byron]

A great many of the aquatic plants we keep in aquaria do indeed release alleopathic chemicals, and to varying degrees. According to Walstad, most allelochemicals are only mildly inhibitory, thus, alleopathy is difficult for scientists to prove. Allelopathy in aquatic pkants is not dramatic. It is subtle. However, all aquatic plants continuously produce a large number and variety of defensive compounds that mildly inhibit all organisms. It is likely that these allelochemicals might have subtle and unrecognized effects on the plants, bacteria, algae, and invertebrates in aquatic ecosystems. [Ecology of the Planted Aquarium, chapter 3]

I have never worried about alleopathy in plants.

 

[sharkweek178]

If the alleopathy were that effective, someone would put it in a bottle as a non toxic weed killer.
The real concern you might have with hornwort is that it grows so fast that it outcompetes other plants for nutrients. But that's a concern you can have for many fast growing plants.

 

[UnityLover]

If the alleopathy were that effective, someone would put it in a bottle as a non toxic weed killer.
The real concern you might have with hornwort is that it grows so fast that it outcompetes other plants for nutrients. But that's a concern you can have for many fast growing plants.

Every plant gets its own root tab or two under it.
3 nutrient shredders: aponogeton, amazon frogbit, and hornwort.
Christmas moss and java fern are the only calm one.

 

[AlexT]

So, is hornwort especially known for this then? I've never seen it singled out in this way?

 

[Byron]

So, is hornwort especially known for this then? I've never seen it singled out in this way?

As i cited earlier, all aquatic plants do have chemicals designed to benefit the plant. Hornwort, species Ceratophyllum demersum, in a scientific study was found to be 60% effective against Lettuce, and 30% effective against Duckweed. Similar numbers apply to many of our aquarium plants.

Some are remarkably effective at this. Nuphar lutea (yellow water lily) in a study actually completely killed Duckweed and Lettuce. Vallisneria americana was 70% effective at killing Lettuce, but only 20% with Duckweed. There are several chemicals these plants use, varying among species, to achieve this end.

 

[AlexT]

As i cited earlier, all aquatic plants do have chemicals designed to benefit the plant. Hornwort, species Ceratophyllum demersum, in a scientific study was found to be 60% effective against Lettuce, and 30% effective against Duckweed. Similar numbers apply to many of our aquarium plants.

Some are remarkably effective at this. Nuphar lutea (yellow water lily) in a study actually completely killed Duckweed and Lettuce. Vallisneria americana was 70% effective at killing Lettuce, but only 20% with Duckweed. There are several chemicals these plants use, varying among species, to achieve this end.

Spooky, but makes sense from an evolutionary perspective. I wish there were plants that would take out the common fish diseases like that, but then again, that might upset mother nature.

 

[10 Tanks]

^^^
If so, how much? Should I wait to add it until everything else is established?

Hello Unity. You may be overthinking the floating plant thing. Your goal should really be a steady water chemistry and not if one small plant is giving off a chemical that may inhibit the growth of another. A steady water chemistry is reached by simply removing and replacing most of the tank water every few days. If you have a small tank, then the water is more difficult to maintain, but you can still remove and replace most of the water twice weekly. The aggressive water change routine will remove most of the toxins and what's left is diluted to a very safe level in all the newly introduced, treated tap water. May I suggest you keep whatever plants suit you and you change most of the water regularly.

10 Tanks (Now 11)

 

[Byron]

Spooky, but makes sense from an evolutionary perspective. I wish there were plants that would take out the common fish diseases like that, but then again, that might upset mother nature.

Well, fish have their own protective strategies, primarily their immune system. The problem is that we the aquarists do not provide fish with what they need, and this causes stress. I have so often written that more than 90% of all disease issues in aquarium fish are preventable but because of the stress we inflict on the fish they succumb.

 

[UnityLover]

Hello Unity. You may be overthinking the floating plant thing. Your goal should really be a steady water chemistry and not if one small plant is giving off a chemical that may inhibit the growth of another. A steady water chemistry is reached by simply removing and replacing most of the tank water every few days. If you have a small tank, then the water is more difficult to maintain, but you can still remove and replace most of the water twice weekly. The aggressive water change routine will remove most of the toxins and what's left is diluted to a very safe level in all the newly introduced, treated tap water. May I suggest you keep whatever plants suit you and you change most of the water regularly.

10 Tanks (Now 11)

Water changes over 50% twice a week? That sounds like it leaves no nitrate, and is actually more harmful. We water change to remove excess nitrate, right? Also, hornwort can grow up to 5 inches a week, so can aponogeton.

 

[Essjay]

That's one of the reasons we do water changes - to remove nitrate. Though in a planted tank, nitrate should not increase above tap water level as the plants take up the ammonia made by the fish so it is not converted to nitrate. Plants themselves only take up nitrate if there isn't enough ammonia and in a well stocked tank the plants have all the ammonia they need.
Terrestrial plants do take up nitrate, this is why people with high tap nitrate often have houseplants growing with their roots in the tank water, as well as aquatic plants submerged in the water.

 

[GaryE]

Water changes over 50% twice a week? That sounds like it leaves no nitrate, and is actually more harmful. We water change to remove excess nitrate, right? Also, hornwort can grow up to 5 inches a week, so can aponogeton.

I do water changes to remove nitrate, but consider it almost as important to remove hormones from fish and plants. That's why I think advising people to only do water changes when their test kit tells them to is a mistake, and why I don't use test kits. They don't tell you much. I know what my water is chemically, and I change it often. If I could do 100% daily with dechlorinated water, I'd do it. 500%? I wish...

Instead, I have my every week routine, and if I have any questions about water quality, rather than hauling out a kit, I do a water change. My plants grow fine.

 

[10 Tanks]

Water changes over 50% twice a week? That sounds like it leaves no nitrate, and is actually more harmful. We water change to remove excess nitrate, right? Also, hornwort can grow up to 5 inches a week, so can aponogeton.

Hello again. When it comes to water changes, more is always better. When you consider the fish are living in the same water they do their "business" in, they need the water removed and replaced regularly, so toxins never build up to the point the immune system is negatively affected. Think about it. If you changed half the water twice weekly, you'd need no filtering system, no aeration equipment and wouldn't need to vacuum the bottom material. That's just three things that you'd never have to do, just because you've established pure water conditions. Sadly, only about one fish keeper in every 100,000 is willing and able to do this.

10 Tanks (Now 11)

 

[GaryE]

Hello again. .... If you changed half the water twice weekly, you'd need no filtering system, no aeration equipment and wouldn't need to vacuum the bottom material. That's just three things that you'd never have to do, just because you've established pure water conditions. Sadly, only about one fish keeper in every 100,000 is willing and able to do this.

10 Tanks (Now 11)

I will disagree strongly with this. You still need oxygen, which comes in via agitated water, and I use many filters to move water for fish from creeks, streams, etc.The number of fish species that come from still water is very small, and we can't meet the needs of most fish by water changes alone. We must look at the needs of each species individually, and if we want them to live well and to show us more natural behaviour, we have to use mechanical means to move water.

A lot of behavioural problems come from pent up energy in fish that should be running in flows (nippy zebra danios anyone?), and a lot of captive fish from fast water end up with obesity issues or lousy muscle tone.

Filters are not just for the cycle. That you can handle with water changes. But for many species, water should move.

 

[WhistlingBadger]

Some are remarkably effective at this. Nuphar lutea (yellow water lily) in a study actually completely killed Duckweed and Lettuce.

Hm, it's a pity my tank is too small to support N. lutea! (I'm having a bit of a duckweed problem at the moment)

Anyway, @Byron , I assume these are fairly recent studies? I seem to remember that the science was inconclusive about aquatic plant allelopathy and no one had quite figured out how to study it scientifically, as you mentioned. I seem to remember that even Walstad referred to it more as an anecdotal phenomenon than as hard science. I could be mistaken about that as it's been a few years since I read her book. I would be interested in reading the specific studies you mention.

Whatever the case, Unitylover, it isn't something to worry about. I usually plant my new tanks with a wide variety of plant species, knowing that over time some will gradually die out and others will come to dominate. I suspect allelopathy is part of this, along with the fact that each tank has slightly different conditions, and some plants adapt better than others. Plant your tank in a way that suits you, add some variety, and see what happens.