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Cladophora - vile weed


17 Jun 2009
So my 60 litre tank has Cladophora in my Fissidens and HC. Quite a bit of it. From what I have read once I have clado, it will keep growing just like a plant. So far I have tried squirting excel on it with the filters off immediately followed by a 4 day blackout. It did turn brown but it has bounced back since. I really do not want to tear down the entire tank because for once my HC and and Fissidens is growing well.

I have some 30% Hydrogen peroxide (H2O2). Should I dilute it and squirt it on ? What are the risks to cardinals and RCS ?

Is there anything I can do to get rid of it ?
Clado has to be attacked by mechanical removal and by overdosing Excel. Of course the root cause has to be addressed as it is due to poor nutrient and CO2 levels. Extra water changes and lower light should help, but ensure dosing is kept up. Eventually it should abate.

I had it in my first tank and got a partial win by lowering the light and removing everything I saw of it with a tooth brush followed by a water change then 3 day black out. That god rid of lots of it, I then kept the light low, added floaters and more biomass and kept dosing of everything else very high. It really is a very difficult one to get rid of but don't lose hope it's possible!
I have already lowered the light by half and increased the nutrient levels by 25 % this past week. I have noticed a slightly slower growth rate but at the same time it has spread to other areas. CO2 is OK DC is green in most areas of the tank (I dont own a DC, borrowed one for a few days). For now I will increase the nutrients some more and I also have a tetratec in the mail to boost flow.

Currently dosing 4ml of AE Carbo a day in 60 L. I will instead do a direct syringe squirt every alternate day. Will keep this up for a couple of weeks and try another blackout. I pull out clumps often enough so that the plants below get some light. prefer doing it by hand as I feel it is gentler than a toothbrush.

What about the peroxide should I give it a go ? If yes then what % and how many ml of that in a 60L, how often and is it fish/shrimp safe ?
Some will disagree, but I would personally advise against using any form of rocket propellant. This substance, if used carelessly, does as much harm to plants and animals as it does to algae. It is as toxic as bleach however it is more biodegradeable.

Just because you have a green dropchecker it does not mean that you have sufficient CO2. In your particular tank, you may need the dropchecker to be in the yellow. I assume you are using 4dKH water in the dropchecker? If not then the green is an illusion.

I guess it was 4dKH solution since it was blue when I got it then turned a medium green with CO2. As I said, I only had it a couple of days since I borrowed it from a fellow hobbyist, not having one myself. Anyways, once I get the new filter, my CO2 diffusion will improve as I will be repositioning the flow to make sure that the bubbles stay in the water column longer.

I will hold off on the peroxide for a while and only use it as a last resort if all else fails. Current plan is lowered light, higher nutrients (Using EI BTW), removal by hand and spot treatment with excel on alternate days for 2 weeks followed by a 3-4 day blackout. Does this sound ok ?
Hi all,
I'm not sure that any of these approaches will really work very well, the problem is that the true green algae like Cladophora (Chlorophyta) are probably ancestral to all the higher plants (so from the Mosses & Liverworts all the way up to the flowering plants - "Angiosperms"), and because of this they share the same photosynthetic pigments and metabolic pathways.

I'd probably go for manual removal and a high plant mass, it is an algae that appears in low tech non-CO2 tanks, but it tends to be a transitory resident and disappear of it's own accord, personally I wouldn't mind a little more in the tanks as it is very good host for a lot micro-organisms, and the threads tend to be heavily colonized by diatoms, rotifers etc. Low tech. tanks tend to get BBA and the only green that is common is a fine fuzz algae which maybe Oedogonium. Interestingly the superficially similar Spirogyra feels really soft and slippery (Cladophora is harder and more wiry) and is almost devoid of epiphytes on it's surface.

Cladophora also grows very well in the buckets of rainwater I have outside, so it isn't inhibited by very low nutrient levels, although Spirogyra won't grow in these, and that may be nutrient related effect.

cheers Darrel
Yes, Clado is tenacious and definitely manual removal is key, along with lots of water changes.

Mortis, your plan is generally a good one, however, if you do not have a dropchecker, how do you manage your CO2 levels? It cannot be assumed that the dropchecker has 4dKh water in it just because it's blue. Tank or tap water would do just about the same thing.

Apologies Mortis for the diversion from your topic, I just wish to touch on a point Clive made.

ceg4048 said:
Just because you have a green dropchecker it does not mean that you have sufficient CO2. In your particular tank, you may need the dropchecker to be in the yellow.

Clive this is one of the aspects of Co2 that I have difficulty in following.

How is it that you would know if you require Co2 to be in the yellow? (this is of course if you are using a 4dkh solution)

Not enough Co2 I can understand, as this would lead to plant deficiencies and or algae blooms.

However, would it not be quite a fine line between, green to lime green, or lime green to yellow.

My own logic would then say to ensure I have sufficient Co2, run levels such that the fish reach critical. From that point decrease the level marginally and lock it.

Yes / No/ Stop being foolish/ Why do they let you out in public.

Hi tel,
Ummm...why do they let you out in public? :lol:
No, just kidding mate. Seriously, there are a couple of really profound reasons that we struggle with CO2. Do you remember the scene in The Matrix when Morpheus was taking Neo to see the Oracle? As they got in the lift, Neo became uneasy with the idea of having his life be validated by a fortune teller. He asks "...is she always right?"
Morpheus's responds; "Try not to think of it in terms of right and wrong. She is a guide Neo. She can show you the path..."

In a way, the dropchecker is like an oracle. It's even shaped like a crystal ball. But it's only a guide. It's never right or wrong. The fact of the matter is that it can only tell you what the pH of the water is just outside the opening. Even at that, it can only ever tell you what the pH was a few hours ago, such is the slow response time.

Now, for someone who has no clue about CO2, having a green dropchecker is invaluable information because it shows that they are on the path. The dropchecker cannot confirm that this absolutely is the right level of CO2 for this tank, under these lighting conditions, under these flow conditions and under these nutrient dosing conditions. Here are some of those reasons;

1. CO2 is tightly linked to the photon bombardment reaching the leaf surface. There is actually a quantitative relationship between the number of photon particles striking the leaf versus the number of CO2 molecules required. The reason is that each strike of a photon adds energy to the pigment where the goal is to energize an release an electron which is then used in a chemical reaction. For the chemical reaction to be complete you must have the appropriate number of CO2 molecules to be involved in that chemical reaction, otherwise the reaction is not completed. If I'm baking a cake, I must have a specific ratio of milk, sugar, floure and so on, otherwise the cake will be ruined.

For illustrative purposes lets put some numbers out there. Lets say in a tank, at a certain distance from the surface, on average, 1 trillion photons per second are absorbed by a leaf. For optimal use of the electrons which are released by these 1 trillion impacts, I may need say, 1 billion CO2 molecules to match. That means 1 billion CO2 molecules must pass across the leaf surface and arrive at the reaction centres every second, just to keep pace with the rate of chemical reactions caused by the photon collisions. If I only send 1/2 billion CO2 molecules to the reaction chambers the plant then has to figure out how to make up that extra 1/2 billion per second.

If I can inject enough CO2 into the water column then I can provide enough partial pressure to create enough CO2 density to send billions of CO2 molecules screaming across the surface membrane to those reaction chambers.

2. Here's where we have the next roadblock. CO2 is a gas. It doesn't care about you or your plants. It follows the gas laws. A higher gas pressure in the water than in the atmosphere means that the more we inject, the faster it escapes to the atmosphere. In this sense, the atmosphere acts as a hoover. So even if the dropchecker shows green, it's showing green as the CO2 is on it's way up and out of the tank! A green dropchecker doesn't mean that 30ppm CO2 is just hanging around looking far a plant leaf to satisfy. Those molecules are getting outta there like a rat out of a trap. If a plant leaf happens to be in the way, well, OK fair enough, the molecule might find itself inside the plant. The plant produces an enzyme called Rubisco that specifically attracts CO2 molecules. It is the job of Rubisco to transport the CO2 molecules to the reaction chambers. So guess what? The plant needs to be able to produce Rubisco. Rubisco is a huge, complicated, slow, lumbering enzyme. It takes a week or two to produce sufficient levels and can only transport maybe three CO2 molecules at a time. The plant has to actually sense the CO2 concentration and then program production of enough Rubisco to match the concentration level of it's environment.

The word Rubisco is an acronym - listen to what this enzyme is actually called:
Ribulose-1,5-bisphosphate carboxylase oxygenase.
Rubisco traps either CO2 (or O2) and mixes CO2 with the chemical called Ribulose 1,5 Bisphosphate (RubP) to produce glucose. This is how plants make sugar for growth. The excess sugar is turned into fruit, vegetables and seed. This is THE definitive behaviour of all plants - to produce food from CO2 using this specific reaction. People just dismiss this reaction - probably the most significant reaction on the planet by saying, "Oh my CO2 is good, my dropchecker is green".

OK so what happens if I add more light? More light means more photons per second colliding with the chloroplast and causing more electron movement. Will a green dropchecker still be sufficient? The green only indicates that there was a certain concentration level, but is that level sufficient for the higher level of photon bombardment?

Can you see why flow and distribution are important? I've got to grab the CO2 before it escapes forever and send it careening into the leaf, quickly. If my flow is anaemic an if I cannot deliver sufficient number of CO2 molecules per second, is a green dropchecker still relevant? I'd actually have to increase the injection rate to compensate for the poor delivery. Higher injection rate means higher escape rate but it also means an increase in density for enough time so that Rubisco can capture CO2. This is why you may need more extreme colour in the dropchecker, because the injection rate has to account for greater loss.

If you drive the lighting too high it's very possible that you then need toxic levels of CO2 in the water column just to satisfy the reaction rate. When you lower the light, you lower the photon collision rate, lower the reaction rate, lower the food production rate - and that's why you lower the growth rate. Now, a green dropchecker is OK, because you don't need as much CO2 in the water. The growth demand is lower.

Algae don't care about any of this because they need 1000X less nutrients and CO2 to survive. They "know" that plant needs are higher and that in a highly lit, poor nutrition, poor CO2 environment, the plants will suffer and die. They will have the whole playground to themselves and they'll be able to feed off the remains of the suffering plants like vultures.

It's always assumed by most that a green dropchecker equates to 30ppm CO2, but that's only true in the water column and mostly at the top. Near the surface of the leaf, the CO2 level that the plant has access to is typically 10X lower than what the dropchecker reads. This explains why we get hair algae even with a green dropchecker. CO2 has to be able to penetrate the waxy cuticle on the leaf surface as well as the spongy membranes of the plant. Quite frankly, it's amazing that aquatic plants are able to obtain enough of what they need at all when you consider these obstacles.

A green dropchecker is not a one-size-fits-all indicator. It is another test kit that can can be deceptive if you are not paying attention to the signs around it. Read the plants first. They will always tell you the score. The dropchecker corroborates your observations. It does not determine them and it must not override them. The rule of thumb is that at lights on the checker should be lime green. If you start to see CO2 related algae then you know that you must either lower the light, or increase flow/improve distribution, or supplement liquid carbon, or increase injection rate, or trim, or, combinations of these.

Hi all,
Good description of the "nuts and bolts" of photosynthesis. RuBisCo is an interesting enzyme, it occurs in all the photosynthetic organisms right back to the Cyanobacteria (BGA), so it originated early in the history of the planet. This is also true of a lot of the other enzymes (and genes that create them) found in all photosynthetic organisms. I've got a lot of references and bits (some written for a non-scientific audience) about the different photosynthetic pathways (mainly in the "green" plants) if any-on wants some more details.

This is from "The cyanobacterial genome core and the origin of photosynthesis" Mulkidjanian et al. (2006) PNAS


It is quite a technical article, but it emphasises the ancient nature of photosynthesis and the core similarities of all the photosynthetic organisms.

"Eighty-four core CyOGs are shared exclusively with plants, such as Arabidopsis thaliana and Oryza sativa, the red alga Cyanidioschyzon merolae, and the diatom Thalassiosira pseudonana. Approximately half of these proteins have known functions and participate in photosynthesis as components of PSI, PSII, light-harvesting systems, or members of the high-light-inducible protein (HLIP)/early light-inducible protein (ELIP) superfamily ...."
cheers Darrel

I do not know why you bother to provide your point of view, to share your knowledge or to encapsulate difficult to explain topics in such a down to earth manner, but I am glad that you do.

You take the time to share your experiences and knowledge, and for that I am grateful.

I do not have to understand your reason, just your explanation, and there is a difference between knowing the path and walking the path.

The relationship between CO2, light and nutrients is a triumvirate that mesmerises me, and I feel that there is much more to it than what I see and understand.

Your posts, and many others here, are indeed the red pill that will show me how deep the rabbit hole really goes.

Obviously I can take the blue bill and keep buying plants and having algae farms on my tank.

Thanks once again for the time taken to distil the relationship between light and CO2.
Ok so Im going to stick to the paln I mentioned earlier. I will also bump up the CO2 from 1 to 1.5 bps. Coupled with the extra flow and better dispersion with the new filter, this should be sufficient. Dont think I could bump it up anymore because shrimp were passing out at 2bps.

Great explaination as always ceg. Any prizes for guessing what your favourite movie is ? lol
Yeah, first one who guess correctly gets a sugar cube. :wave:

Glad you guys find the data useful. Understanding the dynamics of the tank at a fundamental level allows you to see clearly and to avoid drawing illogical conclusions Once you can grow plants algae free, you can then "level up" as they say in PC gaming, so you can concentrate more on scaping and fun things, instead of being mired down in algal mud.

But remember, respect algae, even though you might despise it. The same ferocity with which algae attacks and hangs on to life is responsible for your existence. As Darrel mentions, it was algae that developed out of the toxic primordial seas to pump oxygen into the atmosphere via photosynthesis, so that one day, little mammals could breathe that oxygen and give rise to the evolution of complex bi-peds. That Oxygen feeds the very same complex brain that now contemplates the destruction of algae. What cosmic irony...

In any case, higher flow will enable you to avoid having to drive to higher CO2 concentration levels. Clado will take time to evict. It's more important that you fixed the root cause because we should concentrate on plant health, not on algae. As the plants get healthier due to the changes you have implemented, the Clado will abate. Continue the mechanical removal.

You evolve at level 50 and become a legendary pokemon.

Thanks for the info Ceg, great as always. Good luck with the clado, cegs advice got me over it as did a bottle cleaner, you'll be fine, just be patient. I've read a uv filter helps but that's debatable as it will only kill the spores.
Rather than starting a new thread I just thought I would ask here. Does the Tetratec EX700 need to be placed below the tank or is it OK at the same level ?
Needs to below the tank I'm afraid. Says in the literature with the filter that it may prevent it from drawing any water and overeheat.
What is the length of hose that you get with the filter ?