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Test kits for GH and KH?

Joe Digiorgio

New Member
Hi everyone I’m new here and new to keeping and breeding wild strain apistos and a few other blackwater fish from down that way. I am currently getting into some wild Apistogramma, altum angels and wild Heckel discus. These are projects I’ve been dreaming of for many years.

I’ve been searching here and elsewhere and can’t find consistently recommended test kits for these parameters, especially when working with low numbers. I’ve tried not to even think about my pH as I fully understand the chemistry of very soft water and it’s dynamic consequences regarding pH. I’d love to shoot for 4-5ish but trying to look the other way LOL

My TDS readings are in the high 40s, I do RO water changes weekly to keep it there. I don’t have an exact microsiemens measurement, only TDS and I’d like to use my GH and KH readings as a general guide.

Thanks in advance.
Joe
 

dw1305

Well-Known Member
5 Year Member
Hi all,
.....My TDS readings are in the high 40s, I do RO water changes weekly to keep it there. I don’t have an exact microsiemens measurement, only TDS and I’d like to use my GH and KH readings as a general guide.

Thanks in advance.
Joe
A titrimetric kit like this <"Hanna one">, would be your best bet. I think all Aquarium kits really <"measure alkalinity"> and then assume that most of the hardness is from CaCO3.

I use rain-water in the tanks, and I have hard good quality tap water (from a deep limestone aquifer) so I can use that as my source of hardness. If I didn't have this tap water source I'd use a hard bottled water (they have the analysis on the bottle), if I had more tanks I would use CaCl2.6H2O and KHCO3 to add hardness. The workings are here at <"James' Planted Tank.....">.

It doesn't tell you exactly what ions you have, but I use a datum conductivity level (and plant health) to manage the tanks. I have <"floating plants on all the tanks">, they make maintenance of water quality a lot easier.

You are actually measuring conductivity (in microsiemens) when you get your ppm TDS reading. All TDS meters are really conductivity meters, they just use a conversion factor to estimate "ppm TDS" from the conductivity. The factor is usually 0.64 (general fresh-water), so 100microS is 64ppm TDS. Occasionally the conversion factor might be 0.5 (specifically where the major salt is NaCl), the meter should tell you which conversion factor it uses.

I have access to scientific analytical equipment (and DI water), but I very rarely use them.

cheers Darrel
 

Joe Digiorgio

New Member
Hi all, A titrimetric kit like this <"Hanna one">, would be your best bet. I think all Aquarium kits really <"measure alkalinity"> and then assume that most of the hardness is from CaCO3.

I use rain-water in the tanks, and I have hard good quality tap water (from a deep limestone aquifer) so I can use that as my source of hardness. If I didn't have this tap water source I'd use a hard bottled water (they have the analysis on the bottle), if I had more tanks I would use CaCl2.6H2O and KHCO3 to add hardness. The workings are here at <"James' Planted Tank.....">.

It doesn't tell you exactly what ions you have, but I use a datum conductivity level (and plant health) to manage the tanks. I have <"floating plants on all the tanks">, they make maintenance of water quality a lot easier.

You are actually measuring conductivity (in microsiemens) when you get your ppm TDS reading. All TDS meters are really conductivity meters, they just use a conversion factor to estimate "ppm TDS" from the conductivity. The factor is usually 0.64 (general fresh-water), so 100microS is 64ppm TDS. Occasionally the conversion factor might be 0.5 (specifically where the major salt is NaCl), the meter should tell you which conversion factor it uses.

I have access to scientific analytical equipment (and DI water), but I very rarely use them.

cheers Darrel

Limestone aquifer? Sounds like you’re in Florida like me!

I have avoided using my tap water like the plague. I use only RO not RODI, and have been researching humic, fluvic and tannic acids as additives but haven’t begun using any yet. There is wood in the tanks.

The reason I wanted to start tracking my KH and GH was exactly as you said, I don’t know what exactly is left in the water I’m using. As I understand, and correct me if I’m wrong, it’s KH that I want to keep low or absent for these very soft water species, while GH is less of a concern?
 

Joe Digiorgio

New Member
Hi all, A titrimetric kit like this <"Hanna one">, would be your best bet. I think all Aquarium kits really <"measure alkalinity"> and then assume that most of the hardness is from CaCO3.

I use rain-water in the tanks, and I have hard good quality tap water (from a deep limestone aquifer) so I can use that as my source of hardness. If I didn't have this tap water source I'd use a hard bottled water (they have the analysis on the bottle), if I had more tanks I would use CaCl2.6H2O and KHCO3 to add hardness. The workings are here at <"James' Planted Tank.....">.

It doesn't tell you exactly what ions you have, but I use a datum conductivity level (and plant health) to manage the tanks. I have <"floating plants on all the tanks">, they make maintenance of water quality a lot easier.

You are actually measuring conductivity (in microsiemens) when you get your ppm TDS reading. All TDS meters are really conductivity meters, they just use a conversion factor to estimate "ppm TDS" from the conductivity. The factor is usually 0.64 (general fresh-water), so 100microS is 64ppm TDS. Occasionally the conversion factor might be 0.5 (specifically where the major salt is NaCl), the meter should tell you which conversion factor it uses.

I have access to scientific analytical equipment (and DI water), but I very rarely use them.

cheers Darrel

Limestone aquifer? Sounds like you’re in Florida like me!

I have avoided using my tap water like the plague. I use only RO not RODI, and have been researching humic, fluvic and tannic acids as additives but haven’t begun using any yet. There is wood in the tanks.

The reason I wanted to start tracking my KH and GH was exactly as you said, I don’t know what exactly is left in the water I’m using. As I understand, and correct me if I’m wrong, it’s KH that I want to keep low or absent for these very soft water species, while GH is less of a concern?
 

dw1305

Well-Known Member
5 Year Member
Hi all,
Limestone aquifer? Sounds like you’re in Florida like me!
<"Corsham in the UK">.
I have avoided using my tap water like the plague. I use only RO not RODI, and have been researching humic, fluvic and tannic acids as additives but haven’t begun using any yet. There is wood in the tanks.

The reason I wanted to start tracking my KH and GH was exactly as you said, I don’t know what exactly is left in the water I’m using. As I understand, and correct me if I’m wrong, it’s KH that I want to keep low or absent for these very soft water species, while GH is less of a concern?
Have a look at <"All the leaves are brown">.

The black water has virtually no ions of any description, you could easily have single figure micro-siemen values.

I think that the Ca++ ions are thought to inhibit egg development in some black-water species, but generally it is the carbonate hardness that you need to keep really low.

I haven't successfully bred any black-water fish, probably because even our rain-water has some dGH/dKH. Hopefully some-one who has been successful with them will comment.

cheers Darrel
 

boofeng

Member
My TDS readings are in the high 40s, I do RO water changes weekly to keep it there. I don’t have an exact microsiemens measurement, only TDS and I’d like to use my GH and KH readings as a general guide.

Thanks in advance.
Joe
If your TDS meter isn't getting a high reading, your GH and KH can't be high. GH measures 2+/3+ metal cations, and KH test kits measure total alkalinity (as Darrell mentioned), not just carbonate alkalinity, i.e. all anions of weak acids/bases e.g. bicarbonate, phosphate, etc. All these cations and anions carry a positive or negative charge and contribute to EC readings.

To give you some idea, my local tapwater is TDS 80-100, dGH measures at 3-4, dKH at 2-3. At my previous house less than a mile away, it was TDS 100-120, dGH 4-5, dKH 3-4.

Usually I soak peat in this water and get about the same TDS reading (sometimes a little lower), dGH 2 and dKH 0 (it goes to zero because of how acid peat is). Most apistos I worked with have spawned in this peat water, but I've not worked with species from the extreme black water habitats of the Upper Orinoco and Upper Negro/Vaupes.

Locally, many hobbyists have had Ivanacara adokata spawning and raising fry by using RODI water remineralized to about 50-70 TDS iirc. So, I think your setup should be good! :)
 

Joe Digiorgio

New Member
If your TDS meter isn't getting a high reading, your GH and KH can't be high. GH measures 2+/3+ metal cations, and KH test kits measure total alkalinity (as Darrell mentioned), not just carbonate alkalinity, i.e. all anions of weak acids/bases e.g. bicarbonate, phosphate, etc. All these cations and anions carry a positive or negative charge and contribute to EC readings.

To give you some idea, my local tapwater is TDS 80-100, dGH measures at 3-4, dKH at 2-3. At my previous house less than a mile away, it was TDS 100-120, dGH 4-5, dKH 3-4.

Usually I soak peat in this water and get about the same TDS reading (sometimes a little lower), dGH 2 and dKH 0 (it goes to zero because of how acid peat is). Most apistos I worked with have spawned in this peat water, but I've not worked with species from the extreme black water habitats of the Upper Orinoco and Upper Negro/Vaupes.

Locally, many hobbyists have had Ivanacara adokata spawning and raising fry by using RODI water remineralized to about 50-70 TDS iirc. So, I think your setup should be good! :)

Thanks for the input. The plan is to add leaf litter/seed pods to the display and probably humic extract. I’ll probably put ‘tea bags’ in one of the canister filters. This should remove any KH which I understand is the bad hardness.

Trying my best to take all this in......

What values should I be tracking? I know pH will be relatively hard to track with super soft water, GH seems unimportant as long is its generally low and KH can be assumed to be negligible using RO and humic acids.
 

dw1305

Well-Known Member
5 Year Member
Hi all,
What values should I be tracking? I know pH will be relatively hard to track with super soft water, GH seems unimportant as long is its generally low and KH can be assumed to be negligible using RO and humic acids.
I'd just measure conductivity. I only keep planted tanks so I can use the health of a floating plant to manage water quality.

Black-water makes it more difficult, but there are plants that will grow in very soft water. I'd try Amazon Frogbit Limnobium laevigatum & Ceratopteris thalictroides.

Have a look at <"Tannin Aquatics: Blog"> for some more suggestions

cheers Darrel
 
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