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KH and GH of my tap water

Mitchabbots

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Thread starter
Joined
16 Mar 2024
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42
Location
Trowbridge, Wiltshire
Hello all,
So, bit new to all this aquatics stuff. Thinking of making my own ferts. Have gotten myself stuck at a fundamental level - trying to understand water hardness.

Looking at my Water Provider's (Wessex) website and they specify:

Calcium 110.41 mg/l
Calcium Carbonate 283.67 mg/l
2.84 mmol/l
Degrees Clark 19.86 UK
Degrees German 15.89 dH
Degrees French 28.37 f

Which ones are KH and GH?

I know I have particularly hard water. pH 7.39, Chlorine at 15mg/l, and other water parameters I understand.

Many thanks,
Brian

Update Degrees German is GH is what I've found out.
 
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Hi all,
It doesn't really tell you what the dGH and dKH are empirically, but you can <"make some assumptions"> based on the figures you do have.

Because you live down the road from me, and just off the chalk, I know your water is going to be both hard and alkaline. <"Some handy facts about water">.

_england-wales-jpg.jpg

The calculation, for those who are interested
Calcium 110.41 mg/l
Calcium Carbonate 283.67 mg/l
2.84 mmol/l ........
You can define both "1 dGH" and "1 dKH" as 17.86 mg / L of CaCO3 - <"Water Reports - the Basics, as I am not getting the math!">.
Degrees German 15.89 dH
So we have 284 / 17.9 = 15.89 dGH. You can also use the calcium (Ca) value and 7.143 mg/liter of Ca is also 1 dGH, so 110.4 / 7.14 = 15.5 dGH.

If you use the mmol value, you need the RMM of CaCO3 (which is 40.1 + 12 + (16*3) = 100 g / mol) and divide that by a thousand, which is why the 0.1g or 100 mg = 1 mmol, you have 2.84 mmol and 2.84 x 100 = 284 mg / L or 284 ppm.

The dKH value is also 15.8 ish, because CaCO3 gives a 1 : 1 ratio of dGH : dKH.

<"Wessex Water"> won't quote a separate magnesium (Mg) value, they roll it into the CaCO3 value, but the water won't contain much magnesium ,<"for geological reasons">.
I know I have particularly hard water. pH 7.39, Chlorine at 15mg/l,
The pH will always be somewhere near pH 8 and it is the "chloride" (Cl-) ion, rather than <"chlorine"> (Cl2) gas.

You will also similar amounts of sodium (Na) to chloride, because you get 1 : 1 Na+ and Cl- ions from salt (NaCl), which is derived from the chalk and also from road salting.

cheers Darrel
 
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Thanks Darrel, that's perfect. I recognise the map too.
🙂
Wow! When they said you've a steep learning curve ahead of you (Acres Aquatics). They were not wrong. Enjoying it too.

Thanks again Darrel.

Brian
 
Hi all,
Thanks Darrel, that's perfect. I recognise the map too. .....
You are welcome, to be honest you only really need the map.
When they said you've a steep learning curve ahead of you
Yes and no.

I like to know <"how things work">, but it doesn't necessarily <"make you a better aquarist">.

The rationale for the <"Duckweed Index"> was to <"de-skill fish keeping"> by concentrating on the <"important bits">, the <"coffee not the froth">.

cheers Darrel
 
You're in the same water category as me (Cambridge). If you are going to inject CO2 gas, then you don't really have to worry about the water and lots of plants will grow just fine. Not injecting CO2 gas will be more restrictive (but would be with any water) - the main issue will be you'll have a pH that will need some sort of chelated iron. You'll have a slower growth rate without CO2 anyway so the chelate doesn't have to be too fancy, I have used EDTA-Fe before and not noticed any iron deficiencies. Now I use EDDHSA chelated iron, but mostly out of bloody-mindedness rather than necessity.
 
You're in the same water category as me (Cambridge). If you are going to inject CO2 gas, then you don't really have to worry about the water and lots of plants will grow just fine. Not injecting CO2 gas will be more restrictive (but would be with any water) - the main issue will be you'll have a pH that will need some sort of chelated iron. You'll have a slower growth rate without CO2 anyway so the chelate doesn't have to be too fancy, I have used EDTA-Fe before and not noticed any iron deficiencies. Now I use EDDHSA chelated iron, but mostly out of bloody-mindedness rather than necessity.
Thanks Andy. CO2 is my intention, sat idle while I'm cycling the tank/filter.
I understand my pH has to lower, I've not got round to that part as yet. I do know that CO2 at 30ppm does drop the pH by ~1 (over a few hours). I have a Drop Checker ready to go too.
I'm looking at EI ferts (with perhaps with the Solufeed solution, as identified elsewhere in this forum).
I've taken note of your "chelated Iron" and is on my list of "stuff to research".
I'm glad that others have been asking the same sort of questions and received answers/solutions. Finding them on this forum is the challenge - it is sooooo expansive 😳
As opposed to expensive, which I'm finding this hobby has a way of lightening the wallet somewhat 😆

Best, Brian
 
I like to know <"how things work">, but it doesn't necessarily <"make you a better aquarist">.

The rationale for the <"Duckweed Index"> was to <"de-skill fish keeping"> by concentrating on the <"important bits">, the <"coffee not the froth">.
Me too, I'm very much a strategist and researcher, but that requires a foundation of knowledge to kick off from. I'm all for simplifying the process of keeping nice plants with a few fish. I've got to get my head around the basics, with an eye on the snake oil salesman, to sort the wheat from the chaff. This forum certainly does that.

For me, EI as a start and see where I can go from there as I'm looking to keep aquascaping as pain free as possible. Testing at a minimum, water changes when only necessary and a critical eyeball on what is going on in the tank. Whether EI will last long in my tank remains to be seen. Especially as it promotes an accelerated growth of plants, which I'll want to slow down a bit as the tank gets established.

The Duckweed Index is an interesting take on the balancing act in the tank and reminds me of the old fashioned tuning of the timing of a car. By ear!!
Best, Brian
 
Not this middle one. You should water change generously and if EI dosing a minimum of 50% needs to be changed every week.
Aye, for EI at the beginning. Once I've established the tank I'll re-evaluate. Looking for a balanced system where fish feed the plants, plants feed the fish. With the right amount of fish food and right amount of ferts. Minimal water changes. A challenge for sure, but gonna try 😎
 
Hi all,
Not this middle one. You should water change generously
I'm firmly in the <"water changes"> camp as well. I don't change a large volume, I just change a <"small volume regularly">.
Looking for a balanced system where fish feed the plants, plants feed the fish. With the right amount of fish food and right amount of ferts. Minimal water changes. A challenge for sure, but gonna try
We had a member @Ghosty who talked to Diana Walstad a while ago <"Talking with Diana walstad">, mainly about why she was <"now advocating some water changes"> and water circulation. It is an interesting read - <Walstad revises">.

I'm a <"great Walstad fan">, but I think she <"was initially wrong"> in this case.

cheers Darrel
 
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Hi all,
I've taken note of your "chelated Iron" and is on my list of "stuff to research".
Have a look at <"FE EDDHA"> and <"What is the “Duckweed Index” all about?">.
The Duckweed Index is an interesting take on the balancing act in the tank and reminds me of the old fashioned tuning of the timing of a car. By ear!!
I suppose there are similarities. It won't mean much to younger readers, but I used to spend endless hours mucking about with the timing and mix ratio on cars with SU carburettors (and before anyone asks, alas not on an MG, but on various old, dilapidated and cheap British Leyland cars).

I like the "Duckweed Index" because you get a <"visual representation"> of what is happening (or has happened) and <"a picture"> really is <"worth a thousand words">.

cheers Darrel
 
Hi all,

I'm firmly in the <"water changes"> camp as well. I don't change a large volume, I just change a <"small volume regularly">.

We had a member @Ghosty who talked to Diana Walstad a while ago <"Talking with Diana walstad">, mainly about why she was <"now advocating some water changes"> and water circulation. It is an interesting read - <Walstad revises">.

I'm a <"great Walstad fan">, but I think she <"was initially wrong"> in this case.

cheers Darrel
Not for a moment I was thinking I was going to get away with not doing water changes. That would be the holy grail. However, I feel 50% one a week is excessive, but then EI is maximum dosing which is not sustainable without the changes. Poisoning and saturating the water.

I balk at the 120 litre water changes. That is a very lot of water (bad English, don't care). 20% or 30% was what I had in mind. Once a week is the goal. I know this is not aligned with the EI. Perhaps I should be thinking of another regime.

Best, Brian
 
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