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GH test kit.....does not make sense.....

C

curefan

Member
Joined
11 Feb 2009
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167
Location
Ireland
I want to test my GH to make sure its ok for CRS shrimp, but the instructions make no sense.

Its a Tetratest test kit. Instructions say the GH is the number of drops it takes to turn the colour from red to green!
For starters, my water is not red!!!!!!!!!!!! :bored:
It took 5 drops to turn my water from clear to green, so what the hell does that mean???

Anyone, any idea?

Thanks, Dave.
 
It means when you add the first drop of the test liquid to 5ml of your tank water, the water then turns red then you keep adding the drops until it go's green, Then you have your reading,Well that's what my tetratest does.

If the water doesn't turn red then your test kit may be faulty.
 
billy boy said:
It means when you add the first drop of the test liquid to 5ml of your tank water, the water turns red then you keep adding the drops until it go's green, Then you have your reading,Well that's what my tetratest does.

If the water doesn't turn red then your test kit may be faulty.
Click to expand...


....must be faulty so, or maybe its too old!!!
I wonder can i assume my Gh is 4 since it took me 5 drops to go from clear to green? (first drop is meant to change it to red but it only slightly discoloured mine)
 
The first drop will only turn the water a light red, Then the more drops you add the stronger the red get's until it go's green.
If it's not turning the water red to start with, I would say get a new test kit.
 
viktorlantos said:
Go for a TDS pen. No hassle with CRS then. Just target above 100-120ppm to avoid molting problems and you will be fine
Click to expand...

This wont tell me my GH, will it?
....just total disolved solids???
 
Hi all,
I don't know this actual test kit, but it is the green colour that is important, these are "titrimetric kits". The calcium and magnesium ions form a red compound (at a high pH) when you add the first alkaline buffer solution, as you add more of the indicator solution the weak acid sodium EDTA chelates the metals, and the red colour fades until you have an excess of EDTA, which forms a blue or green colour at the end point of the titration.
This wont tell me my GH, will it? ....just total disolved solids???
Click to expand...
You are right, but in practice Viktor's method works really well. The reason for this is that the TDS pen measure conductivity (in microS) and then uses a conversion constant (in the range 0.5 - 0.64) to estimate TDS.

Unless something strange has happened to the water, (such as going through a "water softener" ion exchange resin where the calcium and magnesium ions would be exchanged for sodium (Na) ions), the conductivity is a fairly good proxy for the calcium ion content, as most of the cations picked up from aquifers are calcium (usually from limestones).

If you are adding fertilisers these will contribute to the conductivity, but in that case, or if you are adding CO2 you should have sufficient calcium present, either from the fertiliser or the dKH you've added to buffer the carbon dioxide/carbonate equilibrium.

Cheers Darrel
 
Hi,
I use a TDS pen exclusively due to the inaccuracies of test kits. TDS seems to be the most important factor from what I've learned from reading about shrimp keeping.
Your local water authority should be able to provide tap water hardness measurements for you, probably with greater accuracy than off the shelf test kits.
Cheerio
Ady
 
Ady34 said:
Hi,
I use a TDS pen exclusively due to the inaccuracies of test kits. TDS seems to be the most important factor from what I've learned from reading about shrimp keeping.
Your local water authority should be able to provide tap water hardness measurements for you, probably with greater accuracy than off the shelf test kits.
Cheerio
Ady
Click to expand...


So if i buy a TDS pen, there is not real need to check the GH??
What sort of value should you be seeing on the pen, with shrimp in mind??
I saw some on ebay, so i might get one,
Cheers.
 
curefan said:
Ady34 said:
Hi,
I use a TDS pen exclusively due to the inaccuracies of test kits. TDS seems to be the most important factor from what I've learned from reading about shrimp keeping.
Your local water authority should be able to provide tap water hardness measurements for you, probably with greater accuracy than off the shelf test kits.
Cheerio
Ady
Click to expand...


So if i buy a TDS pen, there is not real need to check the GH??
What sort of value should you be seeing on the pen, with shrimp in mind??
I saw some on ebay, so i might get one,
Cheers.
Click to expand...
Hi there,
CRS want to be sub 200ppm. And above 120ppm to aid moulting. You can either buy a water conditioner to increase TDS or add RO water to your tap water to reduce TDS depending on what it is out of the tap. If your using pure RO then you will already be adding buffers so just add the required amount to get the ppm TDS your looking for. Other shrimp species such as red cherries etc can live happily in TDS upto 500ppm.
Cheerio
Ady
 
Hi, I was using a tds meter but despite the tds in my tank being perfect my shrimp were dying. It was only when i got an API GHtest I foung that my GH was down at 1! I now use a GH booster made by the nutrient company to maintain my tank at GH6 and no shrimp have died since. I check gh after every w/c to check I've added enough gh booster. They are not breeding though so I've ordered a PH test to check this. In my area of Scotland tap water is tds45, kh0, gh1 and I suspect horribly acidic. Many say test kits are useless but I think where your water is at extremes, tests are necessary. My CRS and CBS are active and growing so great improvement. Think I may have to raise ph though, will wait and see what the test reveal.
 
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