• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

Hardness & algae

I haven't had any green algae in my tank since I started it nearly 3 months ago, but I had plenty of brown algae/diatoms. Some bba too I think after I tried DIY co2.
I have lowered the tds in my tank after my last 2 water changes (using ro water) & now I've noticed that the brown algae has all turned green. My newer leaves still have chlorosis though but I'm hoping the green algae is a sign that iron is now available in the water column.
Are there any root fertilisers that can supply a stable iron in moderately hard water?
 
Water hardness has nothing to do with algae.
It is correct that there are many factors. Hardness is not one that warrants attention.
Do you think this is definitely the case? as i feel from growing in hard water i have experienced excessive occurences of BGA and rhodophyta alongside detritus and silting in my tanks, do you feel it is solely because of the 'humic substances' or does bicarbonate availability have a part to play in all this? interested to hear your thoughts ceg.
a fluorescence analysis revealed that the bicarbonate treatment supported effective photosynthesis, while the CO2 treatment led to inefficient photosynthetic activity with a PSII maximum quantum yield as low as 0.31. Conversely, bicarbonate and CO2 treatments gave similar biomass and fatty acid production.
Umetani, I., Janka, E., Sposób, M. et al. Bicarbonate for microalgae cultivation: a case study in a chlorophyte, Tetradesmus wisconsinensis isolated from a Norwegian lake. J Appl Phycol 33, 1341–1352 (2021). https://doi.org/10.1007/s10811-021-02420-4
 
Do you think this is definitely the case? as i feel from growing in hard water i have experienced excessive occurences of BGA and rhodophyta alongside detritus and silting in my tanks, do you feel it is solely because of the 'humic substances' or does bicarbonate availability have a part to play in all this? interested to hear your thoughts ceg.
Hello Angus,
Yes absolutely. There is no correlation whatsoever between water hardness and algal blooms.
BGA normally indicates either a problem with low levels of nitrate or, as you mention, the buildup of organic waste, which can release ammonia/ammonium into the water column and trigger the blooms. Red algae are usually triggered by poor CO2.

Now, your extract addresses the relationship between the photosynthetic efficiency of a species of algae and bicarbonate, so I'm assuming, when you mention "water hardness", that you are referring to "carbonate hardness (KH)" as opposed to "general hardness (GH)" which are two very different properties.

What we need to realize is that just because an algae is able to metabolize some product in the water column it does not automatically mean that if that product is found in our tanks then an algal bloom will appear. People use this excuse all the time to blame a variety of products in the water column as trigger for algae. The most famous case is the diatom algae, which uses silicates to strengthen it's cell walls. So hobbyists become hysterical about attempting to remove silicates from the water. This never works because the amount of silicates in the water can be practically zero, yet the diatoms will find a way to bloom. The reason is that they are not triggered to bloom simply by the mere presence of silicates. They are triggered by other environmental factors in the tank that may or may not be within our control.

Similarly, BGA and rhodophyta do not really care whether there is a high concentration of carbonate or bicarbonate in the water. They are very small organisms and only require a very small amount of CO3/HCO3 to function. They are not encouraged to bloom simply because of the presence of CO3/HCO3.

The list goes on and on of products that are claimed to be triggers of various algae. Nitrate and phosphate are blamed all the time for various algal blooms, but none of this is true. Fundamentally, we need to keep the tank and filters clean with regular large water changes and we need to feed the plants the proper amount of nutrients based on the configuration of the tank, i.e., low tech or high tech.

By the way, there are plenty of plants that also use CO3/HCO3 as alternate sources of CO2, most famously, Vallis.

Cheers,
 
Yeah sorry i am referring to KH when i say hard water, My vallis is always lovely indeed, we have liquid chalk here.

Rhodophyta induced by poor co2... makes sense i haven't used it in ages, and their other source of carbon is bicarbonates right especially as they are essentially a coralline algae unless i'm mistaken.

Thanks for the in depth reply, loved reading it, so in a non co2 injected tank would you say the existence of bicarbonates could increase algae growth post bloom (as a result of increased build up of decomposing waste) as opposed to a co2 injected tank? if the value's in that study are correct and co2 infact limits microalgal productivity compared to bicarbonates?

i'm very curious is all i'm by no means trying to come to any conclusions myself i'm such a pleb when it comes to science, just trying to draw information out of you ceg... :lol::thumbup:
 
Thanks for the in depth reply, loved reading it, so in a non co2 injected tank would you say the existence of bicarbonates could increase algae growth post bloom (as a result of increased build up of decomposing waste) as opposed to a co2 injected tank? if the value's in that study are correct and co2 infact limits microalgal productivity compared to bicarbonates?

Hi Angus,
Well, algal blooms are symptoms of declining plant health. There is a relationship between algae and plants in our tank. It is a specific relationship and the relationship is different in different environments. That's why it's not a good idea to pull observations from one environment and to automatically apply it to another. So what we observe in our tanks is that the relationship between algae and plants is one of predation, where algae are typically the predators. When plants become weakened the algae attack and we see this as blooms. This isn't the case for every species that bloom but generally so.

I believe the mistake that many hobbyists make is that they assume algae's behavior is based on the presence of these compounds we use instead of looking at the situation from the plants perspective. The result is that they focus on the symptoms instead of the cause. If we want to address algae the best path is to address the plants health. In this sense, it's just as easy for low tech plants to duffer health problems as those plants in a high tech tank.

So for example, in the case of rhodophyta, it isn't necessarily the fact that there is low CO2 in the water, but more importantly, what is the effect of low CO2 on the plants and how they are responding to it. As the plants suffer the effects of poor gas exchange their tissues die and the the algae then attack the weakened tissue. If the plants response to low CO2 was not severe, and if they all had the ability to use CO3/HCO3 as the vallis does then they would remain healthy and would then be able to resist the attacks of algae. The bloom would then be curtailed or may not occur at all. As always, it is the combination of insufficient CO2 combined with a high CO2 demand exacerbated by excessive lighting that generally causes their health to falter.

So it is the level of severity of the condition "low CO2 + high light" that causes the blooms to increase. The algae will not necessarily respond to the level of CO3/HCO3 in the tank. Their needs are satisfied by CO3/HCO3 concentration in the range of parts per billion (ppb) so they really do not care if there is a thousand times more CO3/HCO3 than they need.

Decomposing waste causes other issues, such as lowering of the oxygen content, which plants need at night. This again, is a gas exchange problem that can exacerbate this problem and can cause other problems as well, since cell death can occur under anoxic conditions.

Ironically, over 90% of problems in a CO2 injected tank is actually poor delivery of CO2, so high tech tanks have just as much trouble. High tech-ers tend to use even more light which causes a higher CO2 demand than they can effectively sustain. There is definitely no limiting of algal blooms in these tanks...

Cheers,
 
So it is the level of severity of the condition "low CO2 + high light" that causes the blooms to increase. The algae will not necessarily respond to the level of CO3/HCO3 in the tank. Their needs are satisfied by CO3/HCO3 concentration in the range of parts per billion (ppb) so they really do not care if there is a thousand times more CO3/HCO3 than they need.

Decomposing waste causes other issues, such as lowering of the oxygen content, which plants need at night. This again, is a gas exchange problem that can exacerbate this problem and can cause other problems as well, since cell death can occur under anoxic conditions.

Ironically, over 90% of problems in a CO2 injected tank is actually poor delivery of CO2, so high tech tanks have just as much trouble. High tech-ers tend to use even more light which causes a higher CO2 demand than they can effectively sustain. There is definitely no limiting of algal blooms in these tanks...

Cheers,
After I joined the UKAPS forums this year, I discovered that the key ingredient to a successful planted tank are healthy plants and the 3 key ingredients are:
(1) Good flow
(2) Stable Co2
(3) Clean tank

It's easy to copy someone's lighting setting (Green Aqua's lighting setting is the easiest to copy - they run everything at 100%!), but its not so easy to copy their maintenance routine, tuning of the water flow, and CO2 tuning.

Since the topic is water hardness, there does not seem to be a causative link between hardness and algae. But if you grow a plant that prefers soft water in a hard water tank and don't put in the extra effort to keep the plant healthy, an unhealthy plant is an algae magnet. And it is not necessarily the case that "improving CO2" alone will turn the plant from unhealthy to healthy. (eg: Vin Kutty's 2.0pH drop nosebleed CO2 experiment where he still manage to stunt Lythraceae despite ample CO2)
 
Back
Top