# Hardness & algae



## idris (5 Nov 2021)

Ovwr the last few months I've had a lot more algae than I used to get.
I know there are various factors I can look at but I'm trying to consider what has changed.
A significant difference is that I've moved from tap water to rain water. 

Our tap water is off-the-test-chart hard. Literally. GH>180 and KH >240 with a pH around 7.2
Our rain water is GH<40 and KH<30 with a pH of 6.3

Is the change likely to contribute to algae growth?


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## erwin123 (5 Nov 2021)

I have never seen a website that claims that algae is related to water hardness?
I suppose if your plants are unhealthy because the hardness does not suit them, this is an algae trigger.

by the way, you are on the same journey as Eminor who also has hard water and is turning to rainwater: hard water to soft in one water change ?


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## dw1305 (5 Nov 2021)

Hi all, 


idris said:


> Ovwr the last few months I've had a lot more algae than I used to get. I know there are various factors I can look at but I'm trying to consider what has changed. A significant difference is that I've moved from tap water to rain water.....Is the change likely to contribute to algae growth?


The only thing I can think of is that it might be nutrient availability. The change would mean that ions like iron (Fe++(+)) and phosphate (PO4---) are more available in softer water. 

Before you changed to rain water one of these ions was <"Liebig's limiting nutrient"> because that ion was going out of solution as <"an insoluble compound">. After the change this isn't happening. There is a bit more discussion in <"From Reef to Nature...">. 

I might try upping the plant mass and see what happens. 

cheers Darrel


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## Snowstreams (5 Nov 2021)

I've very hard tap water too with a pH of 7.7 due to my area being karst limestone. 
I seem to have magnesium deficiencys in my plants despite dosing micronutrient fertiliser. 
I wonder could the magnesium deficiency really be an iron deficiency due to the water hardness. 
I might invest in an RO filter or possibly try lowering ph another way.


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## Snowstreams (5 Nov 2021)

Actually I will be starting to add co2 next week once my new lighting arrives. I'm expecting that it will lower the pH quite a bit. 
Would that lower pHincrease the availability of Mg and Fe ions?


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## dw1305 (5 Nov 2021)

Hi all, 
Welcome to UKAPS. 


Snowstreams said:


> my area being karst limestone.


Are you in the Burren?


Snowstreams said:


> I might invest in an RO filter or possibly try lowering ph another way.


I'd really strongly suggest rain water, unless you are very close to the Atlantic? And even then you would only need to discard the water after there had been a big storm, with a lot of salt spray.  Do you have a conductivity (TDS) meter?


Snowstreams said:


> I seem to have magnesium deficiencys in my plants despite dosing micronutrient fertiliser.
> I wonder could the magnesium deficiency really be an iron deficiency due to the water hardness.


Yes, you could have magnesium (Mg), deficiency  mainly because the <"carboniferous limestone"> is fairly pure and doesn't contain <"much magnesium"> for <"geological reasons">. 

Iron (Fe) is a bit different, it needs to be chelated to keep it plant available in harder water, and <"some chelators are better than others"> as the pH rises.


Snowstreams said:


> Would that lower pHincrease the availability of Mg and Fe ions?


It may, if the pH goes below pH7, but even then insoluble compounds will be formed during the CO2 off time period. 

cheers Darrel


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## Snowstreams (5 Nov 2021)

Ah thanks Darrel, 
I'm in Galway near edge of the Burren about 6 miles inland.  There are sheets of limestone under the lawn in my back garden but my water comes from a large lake to the north (lough corrib) that sits on limestone pavement. 
My father used to run a few mass spectrometers in a Uni before he retired (triton icp etc) 
He did run a few tests on the water but I don't remember anything much other than calcium in the results. 
Rain water would be easy to collect here for most of the year, I'll try making a DIY collector during the winter so. 
I'll have to get a tds pen so to help out while I figure out how to manage my water.
I remember from A level chemistry that H+ ions from a strong acid were good to help make most metals more available but I don't think I'll get below ph7 unless I use 75% plus rainwater. 
Cheers, 
John


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## ceg4048 (6 Nov 2021)

idris said:


> Ovwr the last few months I've had a lot more algae than I used to get.
> I know there are various factors I can look at but I'm trying to consider what has changed.
> A significant difference is that I've moved from tap water to rain water.
> 
> ...


Water hardness has nothing to do with algae.
It is correct that there are many factors. Hardness is not one that warrants attention.


Snowstreams said:


> I seem to have magnesium deficiencys in my plants despite dosing micronutrient fertiliser.


On what basis have you concluded that the tank suffers Mg or Fe shortage?
It's better to list the symptoms rather than to conclude a cause.

Cheers,


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## idris (6 Nov 2021)

Thanks all.
I thought it was unlikely, but was just trying to thnink through all possibilities.


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## erwin123 (6 Nov 2021)

Snowstreams said:


> Actually I will be starting to add co2 next week once my new lighting arrives. I'm expecting that it will lower the pH quite a bit.
> Would that lower pHincrease the availability of Mg and Fe ions?


you have mentioned that your tapwater pH is 7.7 but that doesn't necessarily mean that the pH in your tank is 7.7.  Some aquasoils do buffer the pH quite a bit.

My low tech tank without CO2 injection is pH 6.7, but my tapwater is 7.3.


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## Snowstreams (6 Nov 2021)

ceg4048 said:


> On what basis have you concluded that the tank suffers Mg or Fe shortage?


ive attached a photo of the new leaves on a hyrophila corymbosa. 
It used to be very green for its first few months until I tried changing lighting. 
It seems to have dark green veins & pale leaves on its new growth. Its in high flow too if that's a factor.


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## Snowstreams (6 Nov 2021)

erwin123 said:


> you have mentioned that your tapwater pH is 7.7 but that doesn't necessarily mean that the pH in your tank is 7.7.  Some aquasoils do buffer the pH quite a bit.


I've noticed my pH is a fraction lower than my tap water at about 7.4
I'm using a soil that didn't have much nutrients in it (Manado) it does have iron though. 
At one stage I was thinking of using seachem neutral regulator to buffer the pH at 7. 
I don't mind experimenting for a while anyway!


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## ceg4048 (7 Nov 2021)

Snowstreams said:


> ive attached a photo of the new leaves on a hyrophila corymbosa.
> It used to be very green for its first few months until I tried changing lighting.
> It seems to have dark green veins & pale leaves on its new growth. Its in high flow too if that's a factor.


Hello,
          What I can see from the photo you supplied is the yellowing of mature leaves. It is unlikely that this is a micronutrient deficiency as most micronutrients have very poor mobility within the plants. They accumulate in the leaves and they stay there. However, Nitrogen is a highly mobile element. It is also the second most important element and it will move from mature leaves in order to feed the new growth.

It is entirely possible that there are more than on deficiencies, but the most important deficiency, and the one we should suspect in most cases is Nitrogen deficiency. After N is satisfied, if micronutrients are deficient then they will subsequently appear. Therefore, the logical path is to first add N via KNO3 or whichever N nutrient product you have.



Snowstreams said:


> At one stage I was thinking of using seachem neutral regulator to buffer the pH at 7.


Attempting to control pH is another one of those time-wasting endeavors. There is no need to control the pH and it won't help this problem. If you really wish to lower the pH then it would be better to simply add peat granules to the filter as this is a more natural way to lower the pH, but again, is completely unnecessary.

Cheers,


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## Snowstreams (7 Nov 2021)

Thanks for the tips. 
I'm going to try using rain water or maybe RO water along with tap water to lower my hardness. 
I have been using tropica specialised nutrition for the last month to see if it would help. It seems to be high in N and maybe P but the K & mg values seemed low so I thought it might be magnesium deficiency. 
I'll try increasing the dosing for a few weeks & see how it goes.


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## dw1305 (8 Nov 2021)

Hi all,


Snowstreams said:


> ive attached a photo of the new leaves on a hyrophila corymbosa.


That is definitely a deficiency symptom. Technical term is <"Interveinal chlorosis">.


ceg4048 said:


> However, Nitrogen is a highly mobile element. It is also the second most important element and it will move from mature leaves in order to feed the new growth.





ceg4048 said:


> Therefore, the logical path is to first add N via KNO3 or whichever N nutrient product you have.


Potassium nitrate (KNO3) is usually where I start, <"for the reason given">.

If it is a nitrogen (N) deficiency you should get a pretty instant greening once you've added some fixed nitrogen. The <"degree of greeness"> and nitrogen content are <"very closely correlated">.

Because you have interveinal chlorosis, rather than the whole leaf being pale, it is likely to be magnesium (Mg) deficiency (and this maybe as well as <"nitrogen deficiency">). Magnesium is also highly mobile within the plant, so you will get rapid greening if (or when) it stops being defiicient.

Iron (Fe) deficiencies also cause interveinal chlorosis, but in new leaves because <"iron isn't mobile within the plant">.  When iron stops being deficient it takes a while for re-greening to happen, because it is only new leaves, that grew <"when Fe++(+) ions were available"> that will be green.



ceg4048 said:


> Attempting to control pH is another one of those time-wasting endeavors. There is no need to control the pH and it won't help this problem.


Same for me, pH buffers are <"never the answer">.

cheers Darrel


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## Snowstreams (9 Nov 2021)

I've started adding the EI dose recommendation for my all in one fertiliser to see if that helps but I've decided to try adding magnesium sulphate as well to see if that resolves the yellowing issues. 
I'll see how it looks in a week.


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## Snowstreams (20 Nov 2021)

The chlorosis in my hyrophila is still roughly the same as it was 11 days ago when I started dosing magnesium. So I was getting suspicious of iron until today I noticed what looks like an iron deficiency in another hygrophila in my other tank. (See attached image) Up until now this one was fully green but the new leaves are pale. 
I had been using 50% RO water in this tank since I used to have tetras in it but I started using my hard tap water since I added platys to the tank about 6 weeks ago.
My current iron source is tropica specialised nutrition so I'm guessing the iron isn't getting absorbed due to my high pH. From reading in threads here it seems it likely contains the gluconate salt, is that bioavailable in hard water?
So Today I started using 50% RO in both my tanks water changes to try to lower the pH & hardness. (I think I'll collect rain water too since the RO is very slow to fill!)


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## Hufsa (20 Nov 2021)

Iron gluconate is very short lived in hard water, why not just get some DTPA or EDDHA to dose with, and then you can have whatever water parameters you want


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## Snowstreams (20 Nov 2021)

That sounds like an easier option!
Would an aquarium shop or garden centre sell iron dtpa or is it something I'll have to get online?
I don't think my lfs has that wide a range of fertilisers but from their website I see they do sell ferropol which seems to be a chelated form. But probably not dtpa. 
My brother is gifting me an unused 4 channel doser so I'll probably try dosing iron with it on my main tank. 
I wonder would gluconate work in hard water if you dosed it multiple times per day?


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## X3NiTH (20 Nov 2021)

Iron Gluconate works in hard water you just have to be consistent with it, fortifying with a DTPA chelated iron should fill the gaps when dosing every other day, it works for me in GH8 KH8.


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## Snowstreams (25 Nov 2021)

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?


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## Angus (25 Nov 2021)

ceg4048 said:


> 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


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## ceg4048 (25 Nov 2021)

Angus said:


> 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,


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## Angus (25 Nov 2021)

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...


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## ceg4048 (7 Dec 2021)

Angus said:


> 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,


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## erwin123 (7 Dec 2021)

ceg4048 said:


> 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.
> 
> ...


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)


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