CO2 + excessively low PH?

BenjP

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Hi all - first time posting. I have a CO2/Ph-related question I'm hoping someone can help me with.

Currently running a relatively heavily planted 60p tank with CO2. It's been up and running for two and a half months. Light from an ADA Aquasky RGB, filter is a Biomaster thermo 250, and I'm dosing daily with 5ml of Tropica specialised with a 50-60% water change each week. There's also a Twinstar M5 in there. Plants appear to be thriving, and other than a touch of green spot on some of the anubias leaves it's algae-free. Here's a pic from a few weeks back:

upload_2020-5-3_15-31-47.png


My concern is the Ph level, which seldom drops below 5.7, and just prior to lights-on can dip as low as 5.1. In contrast, my tap water generally hovers around 7.2. Here's some info on the tap water in my area of Cornwall, Falmouth, which South West Water tells me falls under 'moderately soft'. I've not measured my GH or KH.

hardness_category_650_wide_fw.png


I'm struggling to understand the disparity between my tap water Ph and that of the tank. Drop checker remains green overnight, so it appears that CO2 simply isn't off-gassing, but there's a reasonable amount of surface agitation and as you can see, I'm using a skimmer.

My question is, how adverse an effect (if any) will this consistently low Ph have on my livestock, which include amano shrimp and horned nerites (I'm sure the ember tetras aren't bothered in the slightest), and what - if anything - should I do to nudge the Ph up a little. Is that even necessary?

Cheers.
 

dw1305

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Hi all,
tap water Ph and that of the tank
It is to do with lack of <"buffering">. You still have soft water (low dKH), but your water company has added a non-carbonate, strong base to raise the pH.

Your water company will add <"sodium hydroxide (NaOH)"> to your tap water to raise the pH. They like NaOH because it is cheap and a strong base. When they inject it goes straight into solution as sodium (Na+) and hydroxide (OH-) ions, it is a strong base there is no residue of undissolved NaOH. pH is a measure of the H+:OH- ratio, you've added OH- (<"a proton acceptor">)
My question is, how adverse an effect (if any) will this consistently low Ph have on my livestock, which include amano shrimp and horned nerites (I'm sure the ember tetras aren't bothered in the slightest), and what - if anything - should I do to nudge the Ph up a little. Is that even necessary?
You can add a source of <"calcium carbonate (CaCO3)">, have a look at <"Nerite snails in high tech">.

cheers Darrel
 

BenjP

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Falmouth
Thanks Darrel, that's really informative and helpful.

Am I best to add something like crushed coral to the filter using a mesh bag? I'm inherently sceptical of companies selling ready-made bottled remedies, but I'm guessing a shop-bought buffer could also do the trick - albeit temporarily?

Cheers.
 
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Zeus.

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Tropica specialised

Trouble I have with this product is I cant seem to find the analysis of it :banghead:

Here's some info on the tap water in my area of Cornwall, Falmouth, which South West Water tells me falls under 'moderately soft'. I've not measured my GH or KH.

any chance of see your full water report? your post code should enable you to download it ;)
 

Zeus.

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dw1305

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Hi all,
Am I best to add something like crushed coral to the filter using a mesh bag?
Because of where you live I'd just go and get some oyster shell. PYO Cuttle "bone" would be another possibility.
I'm inherently sceptical of companies selling ready-made bottled remedies, but I'm guessing a shop-bought buffer could also do the trick
We've got a few <"sceptical" threads">.

You can buy <"Seachem Equilibrium"> or use a <"DIY mix"> of potassium bicarbonate (KHCO3), calcium chloride (CaCl.6H2O) and Epsom Salts (MgSO4.7H2O), have a look at <"James' Planted Tank"> in the link.

cheers Darrel
 

BenjP

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Thanks again Darrel - really helpful.

I’ll give the oyster shells a go, or failing that the crushed coral. I have a friend who keeps a reef tank I can nab some from.

On that note, is there anything to avoid in terms of crushed coral sold for use with marine tanks? I’m guessing aragonite is aragonite...

Cheers
 

dw1305

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Hi all,
crushed coral sold for use with marine tanks? I’m guessing aragonite is aragonite...
Yes exactly that. The only concern with crushed coral is the environmental one. Oyster shell or cockle shell chick grit (to feed to chickens and caged birds) is just a cheaper option for most people.

I use rain-water in the tanks, but I have a good quality hard tap supply, so I can just cut the rain-water with some tap water if I need to add some buffering.

cheers Darrel
 
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Keep an eye on the tropica specialised, although it does contain n and p it is in minute quantities. You tend to find you need to use quite a lot of it to get some decent n values.



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Hanuman

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Indeed.

how adverse an effect (if any) will this consistently low Ph have on [...] horned nerites
Pretty adverse I would say. In other words, premature death.

Nerite shell is not designed to stand acidic environments. Some people say they have no issues but I wonder how that is possible.

Even if you slightly raise your PH, Co2 injected tanks is not really the place for Nerite snails in my opinion. Some other snails have no problem, or at least stand acidity better, specially those who spend their better time burrowed in the substrate. You will most certainly see your Nerite snails escaping the tank on a regular basis. I had to catch mine multiple times several meters away. It's also part of their nature though so it's not only because of acidity.

Want to see the ugly truth? See below. I had 7 of them. Lost the last one a week ago. They lasted around a year (which is not too bad considering they have a 1 to 2 year life expectancy) but I believe they all died prematurely because eventually the shell thinned out and a pin sized holes allowed water to sip inside the shell without restriction.

I know better now. I will never add them again in a Co2 injected tank. Not a place for them.

IMG_2329.jpg
IMG_2328.jpg
 
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