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Rainwater from a butt - de-oxygenated?

The parameters of the tank water before the change were: Temp 25.0°C, TDS 139, pH 6.5, NO₂⁻ 0, NO₃⁻ 40, KH 3°, GH 5°, O₂ 2mg/l

The parameters of the tank water after the change were: Temp 24.7°C, TDS 121, pH 7.0, NO₂⁻ 0, NO₃⁻ ~30, KH 3°, GH 6°

What is the Kh of straight tap water? In order to get a KH 3° in mixed rain/tap water in proportion 9:3, , your tap water must have a Kh 12°, That's nearly double the Kh of my hard tap water here and it looks unlikely to me your tap water has that high of a KH. MgS04 doesn't alter the KH. Unless there's something in the rain water that adds to the KH... which is again unlikely if its pure rain water.

Something doesn't look right to me in those tests and final results. I'd switch the CO2 off for a day next time to get a non-co2 PH of the tank water. Also, you may not be really matching the conductivity/TDS of the new water to the tank water because you are adding MgS04 to the mixture. I know you said it only raises the Gh by 0.5° but I'd be curious to know by how much it raises the TDS of the new water mixture? What's the TDS before and after you add the 10ml MgS04 to that12 litres of mixed water?

Have you tried just ignoring any KH, GH measures, forget about the MgSO4 to match Gh, etc......Don't use any tests bar the TDS meter and mix tap and rain water to get your desired TDS, e.g. 120ppm if that's what you want to be the target long term TDS. This may take a different proportion of tap/rain water, depending on your tap water. For example, my tap water has a TDS of around 250ppm straight out of the tap. To get a TDS of 120ppm I'd need a mixture of 50:50 tap/rain water or just slightly lower on the tap part.
 
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What is the Kh of straight tap water? In order to get a KH 3° in mixed rain/tap water in proportion 9:3, , your tap water must have a Kh 12°
It's been a while since I checked the tapwater GH/KH, because the water is so hard that a test uses up vast quantities of the titration solution. But yes, my tapwater is around 12° KH. If your water measures 6° KH, then that's not what I call hard - I've lived in and around the Thames valley all my life so I'm used to very hard water, with chalk from the Chilterns.

MgS04 doesn't alter the KH.
Erm... I know. I add it purely to increase the GH slightly, for the health of my shrimps.

Also, you may not be really matching the conductivity/TDS of the new water to the tank water because you are adding MgS04 to the mixture. I know you said it only raises the Gh by 0.5° but I'd be curious to know by how much it raises the TDS of the new water mixture?
It doesn't matter in the slightest what effect it has on the new water; the only thing that matters is what effect it has on the whole tank when it's added and mixed with the existing water. Clearly my 'recipe' doesn't cause an increase in TDS to the tank.

Have you tried just ignoring any KH, GH measures
No, I'm not going to ignore GH and KH. KH is important for pH buffering, and GH is important for the formation of my shrimps' exoskeletons. I think you're too obsessed with TDS to the exclusion of anything else.

And if I don't add the MgSO₄ then the resulting TDS will be even lower. So what do you suggest I add in order to prevent that swing?
 
It doesn't matter in the slightest what effect it has on the new water; the only thing that matters is what effect it has on the whole tank when it's added and mixed with the existing water. Clearly my 'recipe' doesn't cause an increase in TDS to the tank.

Of course it does. Your water recipe is as close to your tank water as mushroom soup is to carrot soup. They are both soup but are entirely different.

No, I'm not going to ignore GH and KH. KH is important for pH buffering, and GH is important for the formation of my shrimps' exoskeletons. I think you're too obsessed with TDS to the exclusion of anything else.

I am not obsessed with anything at all. The MgS04 won't help the shrimp. They need calcium. What I am trying to explain to you is that you can't match the stats properly using the liquid test kits. As a result you are swinging the stats without realising it because you trust those test. I won't insist anymore. It's your tank.

As for my tap water...it is hard. I get calcium deposits on the glass..... You don't necessarily need to have a high Kh when the Gh is high. My Gh is around 13-14.

Perhaps if you give the full stats of your tap water, the exact Ph of your tank water without being affected by injected CO2, and the TDS of the rain water, it may be easier for others to help.
 
You're telling me I'm trusting tests too much, yet you're demanding that I test my water more.

Sorry, but you're talking absolute rubbish. I'm close to clicking the 'ignore' link.
 
Oh, and "my GH is around 13-14"

Hahahahahahahaha!!

That's not hard water! You have no clue what it means to live in a truly hard water area!
 
You're telling me I'm trusting tests too much, yet you're demanding that I test my water more.

Sorry, but you're talking absolute rubbish. I'm close to clicking the 'ignore' link.

I asked that you test your water in order to see if what you are adding together makes up what you want to achieve. It doesn't look likely to me. The tests can be used as guidance but that's about it. For some reason when using a GH and Kh test as a guidance when mixing water, one doesn't achieve a consistent result from mixture to mixture.
 
NH₃/NH₄⁺ in the butt measures zero. The tank also always measures zero. I haven't measured the butt pH.


That shouldn't be happening because I'm using Prime as my water conditioner, and dosing a full-tank dose with each water change (largely because it's impossible to measure a smaller quantity). Prime converts ammonia, nitrite and nitrate to much less harmful forms.

I never see any positive ammonia reading, either in the tank water or the new water. I rather doubt that there's enough NH₃/NH₄⁺ around to cause damage, regardless of the pH.
Hi all,They won't be accurate values, measuring most dissolved gases is pretty difficult. You really need a DO meter.

I would assume that your aerated butt water was pretty fully saturated with oxygen, I would be a little bit worried that the level for the tank at night was 1/2 that level. Levels in mg l-1 (ppm) dissolved oxygen can be converted to percentages if you know the water temperature, atmospheric pressure and conductivity of the water, although in fresh water you can ignore conductivity, and to a large extent, atmospheric pressure. Chart below.

nomogram.gif


We use these at the moment <"Hach HQ40d portable..">, with <IntelliCAL™ LDO101 Rugged probes>, these are the best DO meters we've had, but it is quite an expensive option. You still need to calibrate the meter in water vapour saturated air before use, but it doesn't constantly need re-calibration.

cheers Darrel


OK..
One thing which then comes to my mind..

In case of any modern kind of soil (with nutrients "loaded" inside) is used in the tank.. are not the nutrients then actually just waiting to be chemically "set free"..??

and..if a soil contain high values of "reactively prepared ammonium"(in some/any form?) ..will then not some of this "soil-amount" + the normal "tank-amount" from restproducts be released in form of ammonia at once when adding all this new water??
If this is the case..then I also guess the reaction would be more harmful to the fishes/shrimps at a waterchange of 50% than for example 20-30%..??

And..since ammonia also is a gas right..and it might not be able to detect very easily..?? (as Darrel says )

So maybe..?? ....
When adding 50% new water (to the tank-water with pH 6,5) - pH+ammonia might be raised.. and then suddenly dropped again... as a following effect by an active CO2-system..?? (without being detected.. due to the time-factor..fast raise+fast drop!!?? )
If so... An interesting info would be to know how long time passed from the moment you/the Dr. added the new water.. to the moment when measuring the NH4+/NH3 and pH??

and also...
How fast can a CO2 system drop the pH back to below 7 in this situation??? (Ofcourse it is depending on tank-volume, what CO2-system used, the amount of changed water+ all the chemical water parameters...)

This could/would then still explain the panic behaviours of the fishes+ shrimps I guess???

.. and ofcourse.. if any substance/liquid lowering the pH used in the added water..
these effects on the fishes+shrimps will/may hopefully never occur.!!??
 
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Hi all,
What I can't find anywhere is a rough value for oxygen concentration and/or saturation below which fish will start exhibiting increased gill rate. I guess it varies from species to species, but ball-park figure?
Depends on the species of fish but prolonged periods of anything below 2ppm DO is usually regarded as fatal for most fishes, and even short incidents below 5 ppm would impact on salmonids, or really rheophilic Loricariids.

There are some UK figures here <"Environmental Quality Standards for Dissolved Oxygen">.

cheers Darrel
 
Hi all,
That's not hard water!
I think the thing is that once you get past a certain threshold point, for both plants and animals, it doesn't really matter what the exact figures are.

I think for Red Cherry Shrimp the lower threshold is somewhere just below 4dKH/dGH. I've bracketed them together, because most of the hardness in UK tap water is from CaCO3. I have no idea what the upper threshold is, but my suspicion is that it is going to be above the upper limits of any of the tap-water available in the UK.

Threshold values are going to differ from species to species,Crystal Red Shrimp need softer water etc.

I don't know what the exact figure is for the lower threshold for Red Cherry Shrimp is, because I didn't measure the dGH/dKH, but when I found that I didn't have any shrimps left the conductivity had slipped below 60 microS.

cheers Darrel
 
Hi all,Depends on the species of fish but prolonged periods of anything below 2ppm DO is usually regarded as fatal for most fishes, and even short incidents below 5 ppm would impact on salmonids, or really rheophilic Loricariids.

There are some UK figures here <"Environmental Quality Standards for Dissolved Oxygen">.

cheers Darrel
Thanks Darrel.

I've just tested the tank water's O₂ level using the kit. The lights have been on for at least four hours, and both the HC and Glossostigma are pearling and oxygen bubbles are continually rising from them. I assume this means the water is pretty much saturated, which at 25°C should mean in the region of 8.5mg/l. Yet the kit only registers 5mg/l. So there's little doubt it under-reads.
 
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