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Corydoras in hard water...

Fabio Perini

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Addlestone, Surrey
Hi All,

Just wondering if you would consider silly keeping Corydoras Panda in hard water (PH 7.6, GH 13, KH 9). I was thinking of keeping them with Cherry Barbs.
I'm not sure I want to get into the slavery of RO for a bigger tank as I already have one using it and I find having to go to the LFS and pay £3.50 for 25 litre is okay when it lasts you more or less a month for a 30 litre cube but quite doubtful in case of a much bigger tank.
I know I could go for hard water fish but I really like catfish...
Thoughts please?
Cheers,
Fabio
 

tam

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That's not super hard, unless you are trying to breed them, I'd have thought they'd be fine. Buy them locally and they'll be living in your local tap already.
 

Conort2

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They'll be fine. I've kept and successfully bred wild caught corydoras metae in london tap water which is rock hard. Corydoras panda will more than likely be tank bred so should be even easier to keep and breed.

Cheers

Conor
 

sparkyweasel

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Cherry Barbs like the cooler end of the tropical temperatures too, so no problem there. Were you thinking of any more fish species, or just the two?
Maybe danios to occupy the upper levels? They will do well at lowish temps as well.
 

Fabio Perini

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All,

Thanks very much for your kind messages!

I'm an avid reader of most publications and websites like Seriously which is my go-to source to see whether a fish is suitable or not. However, even on Seriously at times, I can't understand the logic. For example, if you look at Paleatus it suggests a tank size which seems too small for them, not sure if it's just a typo or what.

My tank is not ideal for Corys as the footprint is 24"x12" but it's 18" high, at the moment that's what I've got and probably will upgrade to something different in the near future. Hence the Panda. Planning to keep the tank at 22 degrees which should be okay for both Panda and Cherry. What stocking levels would you suggest? I was thinking 6 Corys and 6 Cherry... I would love to get something for the upper section of the tank but I'm worried about overstocking... I'm running a big TowerBlock filter from SwissTropicals 4"x4"x8" which will be more than capable to handle the waste but itself already takes quite a bit of space

I have no intention of breeding them, I don't have the expertise or space. I just would like the fish to be healthy and hopefully live a decent life.

I even thought about mixing RO with tap but I'm not sure if it's a safe option.

I got Unipac Maui fine sand for them. Decent choice?

Many thanks again!

Cheers,
Fabio
 

tam

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You could consider Habrosus - they are smaller. Then maybe 5/6 Ember Tetras or some chili rasbora.

You can mix RO and tap to soften slightly, but really no need.
 

mort

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I keep panda and adolfoi cories in a 24x12" tank and they do well. They are a small species and I keep nearly all the substrate clear of decor, apart from some twigs and leat litter. I maintain a minimum temp of 22c and they breed without intervention. I do use partial RO for water changes but am slowly transitioning the tank to pure tap water (which is similar to yours) because it makes everything so much easier. Tank bred cories are pretty happy in anything.
 

dw1305

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Hi all,
Corydoras Panda in hard water (PH 7.6, GH 13, KH 9).
I think they are fine in harder water. The tap water locally is about 17dKH, and I know a number of people who breed them in it. They don't like it too warm, but other than that they are pretty adaptable.

Fish from the Andean piedmont or Panatanal (S. or W. of the main Amazon basin) are usually OK in harder water, it is the ones from the central Amazon basin (Rio Negro drainage etc.) that need really soft water.

cheers Darrel
 

Fabio Perini

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I think they are fine in harder water. The tap water locally is about 17dKH, and I know a number of people who breed them in it. They don't like it too warm, but other than that they are pretty adaptable.

Hi Darrel,

I have a question for you regarding the water supply. I was talking to the manager of the Waterlife shop in West Drayton and he said that due to the PH swings in their water supply they buffer the water to make it suitable to the fish they are selling, trying to reproduce the water parameters of the breeding farms.
Now, the cynic in me thought he was trying to promote the Waterlife PH buffering product, and a very expensive too: 10 quid a pop to treat just 300 to 400 litres of water!
How much truth is there in the statement that the PH of the water supply swings significantly? And if there is some truth in it, how do we protect our fish when using tap water?

is 17dKH referring to my area? I couldn't really find the figure in the water quality report from Affinity, I guess you need to calculate that from other parameters.

This the summary of my supply zone...


Water Supply Zone: Weybridge/Woodham (AF067) Period: 01-Jan-2017 to 31-Dec-2017


This information is taken from historic results of monitoring and may be subject to change. This information is provided as a guide only and is subject to our terms and conditions.


HARD WATER
The area supplied by Affinity Water has 'hard' water. The hardness occurs naturally and is characterised by the presence of high levels of calcium and magnesium, which are good for healthy teeth and bones.
CALCIUM 115 mg/l
Calcium is the principal constituent of hardness.
TOTAL HARDNESS 287.5 mg/l
Total hardness is usually expressed in terms of calcium carbonate and is measured in milligrammes per litre (mg/l) which is the same as parts per million (ppm). The recognised classification scheme we are using is: 0-75 soft, 76-150 moderately hard, 151-300 hard, 300+ very hard. Your water is hard.
Degrees English (or Clarke) 20.125
This hardness measurement is used on some British appliances.
Degrees German 16.1
This is used on some German appliances.
Degrees French 28.75
This is used on some French appliances.
MILLIMOLS 2.875 mmol/l
Millimols per litre. Some appliances refer to water hardness in millimols per litre (mmol/l).
FLUORIDE 0.152 mg/l
Fluoride naturally occurs in the water in many areas. Affinity Water does not add any fluoride to your water. Fluoride is measured in milligrammes per litre (mg/l).


Thanks in advance for your time.

Cheers,
Fabio
 

Fabio Perini

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I keep panda and adolfoi cories in a 24x12" tank and they do well. They are a small species and I keep nearly all the substrate clear of decor, apart from some twigs and leat litter. I maintain a minimum temp of 22c and they breed without intervention. I do use partial RO for water changes but am slowly transitioning the tank to pure tap water (which is similar to yours) because it makes everything so much easier. Tank bred cories are pretty happy in anything.

Hello Mort,

Thanks very much for the information which is quite comforting. How long have you been keeping the Panda and Adolfoi in the 24x12 tank? How many of them do you keep? Is it a Corys only tank? Out of curiosity, what do you do with the offspring?
When you say you do partial water changes with RO, were you doing a 50/50 split or different? Was the tank setup initially as tap only or did you have RO in it from the start?
I assume the tank to be planted?
Sorry for the many questions, just very interested in your setup.
Thanks in anticipation for the insight.
Cheers,
Fabio
 

Fabio Perini

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You could consider Habrosus - they are smaller. Then maybe 5/6 Ember Tetras or some chili rasbora.

Hi Tam,

Thanks for that.
I do like Habrosus and I will have a tank for them, however as they are wild caught I would use RO in that case. I already have Chili Rasboras in an extremely soft water tank with zero KH, buffered by Shirakura Bee Sand. They are doing fantastically well and their coloring is from another world! I doubt they would do as well in tap. They live with a colony of shrimp and they don't seem at all interested in eating the shrimplets considering the massive breeding that is happening in the tank. I do like Ember Tetra and surely they seem able to adapt to a huge range of parameters.
Cheers,
Fabio
 

tam

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How much truth is there in the statement that the PH of the water supply swings significantly? And if there is some truth in it, how do we protect our fish when using tap water?

It can appear to swing if you measure straight from the tap and after it has stood awhile. To do with the change in CO2 levels I think. In some areas water can come from different sources at different times so can have different parameters.
 

dw1305

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Hi all,
I have a question for you regarding the water supply. I was talking to the manager of the Waterlife shop in West Drayton and he said that due to the PH swings in their water supply they buffer the water to make it suitable to the fish they are selling, trying to reproduce the water parameters of the breeding farms. Now, the cynic in me thought he was trying to promote the Waterlife PH buffering product, and a very expensive too: 10 quid a pop to treat just 300 to 400 litres of water!
I'm cynical too, and <"I have a real problem"> with a lot of the sellers of aquarium products, they sell cheap chemicals, at an enormous mark-up, to rectify problems that don't really exist.

If you have hard tap water the pH will be fairly stable and about pH 7.8 - pH 8.2. This value is reached because it is the equilibrium pH value for the <"carbonate ~ CO2"> buffering system at ~400 ppm atmospheric CO2.

pH will show a diurnal rhythm in a planted tank (without added CO2). During the photo-period the plants are net oxygen producers and the water is depleted of CO2, and the pH will rise, during the night all the bioload is respiring, oxygen levels fall, CO2 levels rise and pH falls.

When you add CO2 you change the pH equilibrium point, so the pH is lower. I'm not a CO2 user, but those who are will tell you that a fairly rapid change of one pH unit (down at gas on, up at gas off) doesn't effect the fish, which probably tells you all you need to know.

CO2 ~ carbonate is a buffered system, which is why we have a stable pH value, and there are other pH buffers that will maintain pH at a specific level. I've never used the Waterlife pH buffers, but they are almost certainly based on <"phosphate buffers">, and probably NaH2PO4 and Na2HPO4.

The only thing these products do is separate you from your money.
How much truth is there in the statement that the PH of the water supply swings significantly? And if there is some truth in it, how do we protect our fish when using tap water?
You can just ignore pH, if you change some water fairly regularly you will always have hard water in the tank.
is 17dKH referring to my area? I couldn't really find the figure in the water quality report from Affinity, I guess you need to calculate that from other parameters.
The 17dKH was for Corsham where I live, but it will be a similar value for all of the water that comes from a chalk or limestone aquifer, so most of the S. and E. of England. It is back to the equilibrium value for the CO2 ~ carbonate buffering system.
CALCIUM 115 mg/l Calcium is the principal constituent of hardness (dGH).
TOTAL HARDNESS 287.5 mg/l...The recognised classification scheme we are using is: 0-75 soft, 76-150 moderately hard, 151-300 hard, 300+ very hard. Your water is hard.
Total hardness is usually expressed in terms of calcium carbonate and is measured in milligrammes per litre (mg/l) which is the same as parts per million (ppm). ....Degrees German 16.1......
These are the values you need, your dKH is 16.1.

If you wan't the working for how you can work out how calcium, bicarbonate and hardness relate to one another they are in <"this post">.

cheers Darrel
 

dw1305

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Hi all,
I already have Chili Rasboras in an extremely soft water tank with zero KH, buffered by Shirakura Bee Sand.
I should have said that I keep soft water fish and that I use rain-water in my tanks, I occasionally cut it with some tap in the winter and some RO in the summer.

I don't measure pH or hardness I just keep the tank water conductivity within a 80 - 150 microS range.

The active substrate can soften the water via ion-exchange, there is a more complete discussion in <"Still very......">.

cheers Darrel
 

mort

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Hello Mort,

Thanks very much for the information which is quite comforting. How long have you been keeping the Panda and Adolfoi in the 24x12 tank? How many of them do you keep? Is it a Corys only tank? Out of curiosity, what do you do with the offspring?
When you say you do partial water changes with RO, were you doing a 50/50 split or different? Was the tank setup initially as tap only or did you have RO in it from the start?
I assume the tank to be planted?
Sorry for the many questions, just very interested in your setup.
Thanks in anticipation for the insight.
Cheers,
Fabio

Hi Fabio,

The tank was setup with an RO tap mix of 70:30 because I was using it for breeding some wild apistogramma. I moved them on and just had 6 adolfoi in there. Since then I've been slowly changing the water by upping the tap percentage every water change (about 50% once a fortnight). I added the Panda cories a couple of months ago when I shut their tank down and have six beckfords pencilfish in there as well.
The plan is to eventually have a group of ten of one species, probably the adolfoi and create a similar tank for the others so I can get the breeding going. At the moment I have had 10 adolfoi cats survive without my intervention and gave some to a friend to breed and swapped some for some adults at a lfs to stop cross breeding.

The tank is a blackwater type setup with a little leaf litter, some buce and mosses tied to the twigs with emergent growth. This is really just a trial tank to see if I want to do the same thing on a larger scale. If I do I'll keep the two cory species and add more pencilfish above them.
 

Fabio Perini

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I'm cynical too, and <"I have a real problem"> with a lot of the sellers of aquarium products, they sell cheap chemicals, at an enormous mark-up, to rectify problems that don't really exist.

Darrel,
You're quickly becoming a hero of mine! :clap:
You confirmed my suspicion that the guy was talking nonsense! And you've put my mind at rest as at first, I got really worried I was doing it all wrong...
Thanks ever so much!
All the very best,
Fabio


I don't measure pH or hardness I just keep the tank water conductivity within a 80 - 150 microS range.

I assume you use a TDS meter to measure the conductivity? Are those fairly cheap TDS pens good enough? What would you recommend to have reliable readings?

I'm trying to get away from active soils as I've realised they are time bombs as you never know when they will get totally depleted causing your tank to crash (in case of no KH)... Any pearls of wisdom on that? My tank has been running for two years now and from what I hear people tend to change the active soil for shrimp approx. once a year just to make sure. I don't have patience with that so I'm going to move to sand and mix tap and RO.
Cheers
 

Fabio Perini

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The tank was setup with an RO tap mix of 70:30 because I was using it for breeding some wild apistogramma. I moved them on and just had 6 adolfoi in there. Since then I've been slowly changing the water by upping the tap percentage every water change (about 50% once a fortnight). I added the Panda cories a couple of months ago when I shut their tank down and have six beckfords pencilfish in there as well.
The plan is to eventually have a group of ten of one species, probably the adolfoi and create a similar tank for the others so I can get the breeding going. At the moment I have had 10 adolfoi cats survive without my intervention and gave some to a friend to breed and swapped some for some adults at a lfs to stop cross breeding.

Hi Mort,

I assume your tap is already fairly soft? Or is it hard like mine? I do like Corydoras Duplicareus which is similar in size to the Panda, but, as Darrel mentioned that would require soft water as it comes for the upper Rio Negro.

How did you source your Panda and Adolfoi?

Cheers,
Fabio
 

mort

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Hi Mort,

I assume your tap is already fairly soft? Or is it hard like mine? I do like Corydoras Duplicareus which is similar in size to the Panda, but, as Darrel mentioned that would require soft water as it comes for the upper Rio Negro.

How did you source your Panda and Adolfoi?

Cheers,
Fabio

Our tap water is described as very hard by our water company.

My panda were picked up from a lfs and are tank bred imports. The adolfoi are also tank bred and were a special order. I've had them a few years now but they seem available quite often.

If you can do RO then it's good but I often see people advise that tap is so much easier. I have RO because I make my own for my marine tank anyway so it's easy, the waste is collected to water my garden, but it is nice to be able to simply use tap if need be. This winter I'm building some rain water collection for the tropical tank so might probably will stop my transition to tap water (it's something I only decided yesterday as a winter project and would expand what I could keep in the future).
 

dw1305

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Hi all,
You confirmed my suspicion that the guy was talking nonsense!
The subject areas of "pH", "pH measurement" and "fishes sensitivity to pH change" are really contentious. Part of the problem is that pH is both a <"log10 scale and a ratio">, which means that two similar pH readings may occur in very different water, or that two very different pH recordings can come from the same water at different times.

I look at changes in pH in terms of changes in water chemistry. As you move towards pure H2O (rather than the dilute solution of salts, with H2O as the solvent, that we usually call "water") pH becomes less and less meaningful as a measurement. In very soft water small changes in water chemistry cause large changes in pH, but in hard (carbonate buffered) water large changes in water chemistry are required to lower pH.

Before aquascapers started adding CO2 to tanks everyone would have said that a fall of pH from alkaline (~pH7.8) to acid (below pH7) in an hour will kill all your fish, but this has proved to be untrue. Changes in pH, caused by addition of CO2, are changes in the the amount of TIC, you have more TIC, and a larger proportion of that TIC is carbonic acid (H2CO3), and the pH falls, nothing else has changed.

A measurement of pH is really only useful if you have some idea of the carbonate buffering (the dKH) of the water.
I assume you use a TDS meter to measure the conductivity? Are those fairly cheap TDS pens good enough? What would you recommend to have reliable readings?
Yes, a cheap conductivity meter will give you a fairly accurate reading, you need a <"low range meter"> (0 - 1999 microS).

It isn't going to apply in absolutely every situation, but usually a high conductivity value (600micro S - 800 micro S) for your tap water indicates that the water is "hard" and pretty fully saturated with Ca++ and HCO3- ions (has high dGH and dKH), even higher values usually indicate there are other non-carbonate salts present as well (from EI, salt ingress or agricultural fertilisers etc.).

cheers Darrel
 
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