Corydoras Pygmaeus water paramters

[Samdaark]

Hi guys, I looking for thoughts on whether my water parameters would be suitable for Corydoras Pygmaeus, so that they would be super healthy and also provide good conditions for breeding.

Water parameters are:
- Temperature: 25'C
- KH: 2-3 'dKH
- GH: 8-9 'dGH
- PH: 6.2
- NH4/NO2/NO3: All close to zero

Just for context I am remineralising RO water with Salty Shrimp Soft Water Minerals (http://www.saltyshrimp.de/english/soft_ ... _plus.html) so able to adjust things or move to alternatives if any of you have a better recommendation for products like this that would suit.

Many thanks,
Sam

[dw1305]

Hi all,

.......whether my water parameters would be suitable for Corydoras Pygmaeus, so that they would be super healthy and also provide good conditions for breeding.

Water parameters are:
- Temperature: 25'C
- KH: 2-3 'dKH
- GH: 8-9 'dGH
- PH: 6.2
- NH4/NO2/NO3: All close to zero............

You can't really tell from there, can we have a tank picture?

Is it a planted tank? Others may disagree but I wouldn't try to keep them in an unplanted tank, unless it had a lot of structural leaf litter and you were very good at maintaining water quality.

Have a look through the breeding reports on the clog page "

Corydoras(ln4) pygmaeus

" and at "Food for Corydoras pygmaeus". I have some at the moment and they (risking the kiss of death) are doing very well. I keep them in soft water, 100% rainwater with a minimal "addition of plant fertilisers" and mainly live food. The conductivity is about 120 microS (~80 ppm TDS) and I don't measure any other parameters. I get some dGH and dKH from my rainwater, because it is all limestone here, and I have a hard tap supply I can add if conductivity fall below ~60 microS.

.......Just for context I am remineralising RO water with Salty Shrimp Soft Water Minerals............

The water parameters are a bit strange, once you have some carbonate buffering the dKH the pH should rise to over pH7 and you would expect to have some nitrate (NO3) readings, but I'm not familiar with "Salty Shrimp".

You can raise hardness with a simple salt mix, have a look on "James' Planted Tank".

cheers Darrel

[Samdaark]

Thanks Darrel.

I've included a pic of the tank in question (the one on the right) where there are around a dozen Pygmy's.

Pygmy tank on the right

By the sound of things you are suggesting my water is a bit low on the carbonate and PH for these guys, which isn't a problem since my London tapwater is hard as a rock and i can cut some with the current RO mix I'm using to raise the levels a bit. My TDS is pretty similar to yours by the look of things, sits around 100ppm.

I was actually wondering if I should aim for more a neutral PH for these Cory's, rather than try to simulate some of the very soft lower PH conditions, which may not be necessary for these Cory's I'm guessing.

Thanks again,
Sam

[dw1305]

Hi all,

Thanks Darrel.
I've included a pic of the tank in question (the one on the right) where there are around a dozen Pygmy's.

That looks perfect.

By the sound of things you are suggesting my water is a bit low on the carbonate and PH for these guys, which isn't a problem since my London tapwater is hard as a rock and i can cut some with the current RO mix I'm using to raise the levels a bit. My TDS is pretty similar to yours by the look of things, sits around 100ppm.

Sam

No, I reckon 100 ppm TDS is fine, I definitely wouldn't go any higher. I don't worry too much about any of the other water parameters, other than conductivity. In really soft water pH will always be unstable, but this isn't a problem for the fish.

As a general point I'd really like to know how much NO3, DO I have etc., but I've been involved in some water quality monitoring, so I appreciate that these measurements are much more problematic than many forums etc would suggest.

cheers Darrel

[JenMorri88]

Damn, just looking for the same !. This is a coincidence))) When someone tells me, if I suddenly don't see it, write to me. I even went to this forum to write this hahahaha

[Samdaark]

Yeah i agree in terms of the NO3 and other nitrates, I've learned the hard way that Pygmy's can definitely be sensitive to those and I've lost a whole colony previously as a result of even moderate concentrations.
Nothing beats crystal clean water and I keep an eye out for any signs of algae, especially BBA and the like as a warning that something is up with the nitrates.

I think by the look of your tank Darrel, you are also a big fan of heavily planted tanks for Pygmy's, both for their comfort but also as a way to reduce the nitrates...

[dw1305]

Hi all,
@Samdaark, yes all my tanks are heavily planted.

That one is particularly stuffed, because it has a more powerful light on it and I let the plant mass develop layers until all available PAR is utilised. I'm pretty sure the Pygmy Corydoras wouldn't mind if that structure was mainly leaf litter rather than plants. The only other residents are some Copella callolepis (Zarske).

I like plants (I trained as a botanist), but I'm mainly interested in them in the fish tank as a mechanism for maintaining water quality.

cheers Darrel

[Samdaark]

Hi Darrel,

I've been spending a lot of time based on your previous advice, especially in terms of using the water conductivity as the primary factor for getting my water conditions right. Sadly I realised that my TDS meter was giving some very inconsistent results and hence why I think you originally mentioned in an early post that my water parameters seem a bit strange. I've purchased a new and much better quality meter now which is showing readings that have answered some issues I was seeing when trying to get the water right.

Something I wanted to check with you as it appears you know a lot about planted tanks, is your experience on injecting CO2 in aquariums that have very soft water and whether when maintaining a TDS of say 80ppm whether you have seen any issues with regards to how this might further affect the water chemistry balance.

I am considering CO2 for the tank but know with low KH this might cause some pH swings. Any views on whether injected CO2 in very low TDS water can work or is it better to avoid altogether?

Cheers,
Sam

[Bas Pels]

I would never use CO2. Because it is the stuff our fish breath out, putting more of it into the water will make it harder for the fish to get rid of their waste product, resulting in more acidic blood.

Now if one needs a low pH, there are other, better solutions. lowering the pH with peat, old leaves, whatever natural stuff is much better. Basicxally, the natural stuff will result in humic acids, which are beneficiary for fish from low pH areas.

Whatewver the method of lowering the pH, it will always result in a low KH (the higher the pH, the higher the percentace of the CO2, HCO3- CO3-- system is in the carbonate shape, which is what KH measures. Regardless the pH the same amount of CO2 dissolves, but in case this is 100 %, or 10 % of the total will matter a lot) but lowering the acidit with humic acids will leave the acid in the tank.

This will have its own buffercapacity. Less strong than the carbonate buffer @ pH = 7, but it is active.

[dw1305]

Hi all,

I would never use CO2. Because it is the stuff our fish breath out, putting more of it into the water will make it harder for the fish to get rid of their waste product, resulting in more acidic blood.

..........is your experience on injecting CO2 in aquariums that have very soft water and whether when maintaining a TDS of say 80ppm .....is it better to avoid altogether?

I'm definitely in the "avoid camp" as well.

I don't actually have any practical experience of CO2. I'm not a CO2 user (and I never will be), mainly because I can find quite enough ways to accidentally kill my fish without adding another, entirely avoidable, one.

One of the reasons I'm so keen on floating plants is that they aren't ever CO2 limited.

As @Bas Pels alludes the pH drop you get when you add CO2 is slightly different from the pH reduction you get in other circumstances. The chemistry of the carbonate ~ CO2 ~ pH equilibrium isn't entirely straightforward, but the pH reduction is because you have increased the amount of Total Inorganic Carbon (TIC) in the system. A very small proportion of that extra CO2 becomes H2CO3 and that disassociates into a proton (H+ ion) and a bicarbonate (HCO3-) ion, acids are defined as "proton donors" and the pH falls.

There are issues with pH measurement in low electrolyte water, but there are also inevitably swings in pH, this happens in our tanks and <"in nature">.

cheers Darrel

[Samdaark]

Thanks Bas Pels and Darrel for sharing your experience and perspectives on this. I'm really glad to have asked this now as it has definitely turned me off going down the CO2 route, which now confirms my worries about what effects on the water parameters and especially the fish this can have. Thanks both I think you've saved me avoiding a lot of stress in the future!

Sorry to get further clarification on the original topic but since I now have more accurate ways to measure my TDS, and on a good day my tap water is 300ppm (sometimes up to 450 at certain times) so I cut it with RO water. As you know I'm still on the journey of learning about water chemistry and I would like to clarify with you something when it comes to TDS, GH and KH.

When my tap water is 300ppm TDS, it generally has a GH of about 18 and a KH of about 12, pH 7.7.
If I want a target water for my aquarium of say 100ppm TDS, that means cutting 1 part tap water to 2 parts RO water, would be what I understand is required (btw my RO water is basically reading 0 TDS).
Does this then mean normally that as a result I would see my GH in this water go to 6 and KH to 4?

Sorry if I've made that question ridiculously complex or made some wrong assumptions but while I am taking the advice of focusing on TDS as the main water parameters I just want to make sure that I understand what happens within the water when we dilute it like this.

Many thanks again guys, I don't think you realise how much help you are and how many fishes lives as a result are improved or saved by these discussions

Cheers,
Sam

[Bas Pels]

Hardness, just as conductivity (your TDS measurement is a condictivity measurement) are all linear scales.

That is, if 2 units are around, the reading will be twice as high. So yes, 2 parts RO and 1 part tapwater of 18 GH will make 6 GH in total.

pH is another matter. Firstly the scale is logarithmic, that is in pH 6 the amount of H+ is 10 times the amount in pH 7, further, the pH is effectively always somewhat buffered. Lastly, CO2 from the air will dissolve in RO water, lowering the pH - but as this is not buffered, the effect will be small.

Most likely, 1 part tapwarter and 2 parts RO water will have a pH similar to the original tapwater. Your 7.7 could be 7.6 for instance.

[dw1305]

Hi all,
Exactly what @Bas Pels says.

My guess is that your dGH / dKH values will be more similar to each other, just because the hardness in the SE UK is from chalk (CaCO3) and that supplies a 1:1 ratio of dGH : dKH.

cheers Darrel

[Samdaark]

Thanks again guys, really appreciate your advice and time on this.

Cheers,
Sam