PH Changes and PNG Rainbows, I'm Confused

Seeing that noone really said anything in response to the point i brought up earlier (and without wanting to HJ this thread - sorry) - can i conclude that it doesnt matter if my tank water is high kH because it was brought up with crushed coral (as an example) and then i do a large waterchange with low kH tap water. This drop in TDS and pH wont cause any osmotic pressure and result in stress for the fish ?
 
You need a separate bubble counter that is external. you do not have to buy a Milwaukee or JBJ regulator just to get a bubble counter. Aqua medic and Ultralife both make a bubble counter. Even JBJ has one that does not screw onto their regulator. If you search the internet, you can find someone selling them. I am going to start selling Aqua medic C02 equipment again in a month.

Having a higher KH level means you can add more C02 to the water, but your pH may still be lower than what you want, but it really should not matter for the fish. pH plays more of a role in breeding than in general fish health, unless you go extreme. I have never know rainbow fish to be that sensitive.

I do not know what PNG rainbows are? I kept a rainbow tank of 8 different varieties back when I lived in California. The water there was kinda hard, but I injected C02 bringing the pH down to 6.8. No problems what so ever.

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Lemme see if I'm understanding this:


1. Hard water is water that has a high mineral content, usually of metal ions, calcium and magnesium in the form of carbonates, but can also contain other metals as well as bicarbonates and sulfates

2. pH is the measure of activity of hydrogen ions in a solution; its acidity or alkalinity and is not based on the amount of calcium and magnesium

3. Fish don't read pH. Fish read TDS -- total dissolved solids (carbonates, magnesium etc.,.)

4. TDS means more to fish than pH

5. Generalizing: Fish that naturally occur in high pH water (8.0+) ie. Rift Lake, are actually in a much higher TDS than most fish.

6. Fish that occur in a naturally low pH water (6.0 or whatever discus like) are actually in a much lower TDS containing water which is solved by using an R/O unit which removes everything but the bathroom sink

7. Many fish who prefer a higher TDS are often thrown in salty or brackish conditions in order to "mimic" their natural environment. Mollies, for instance, prefer a harder water, but are thrown in salt conditions because people feel that it is the same as their natural environment

8. GH is a measure of general hardness, the amount of calcium and magnesium

9. KH is a measure the carbonates and bicarbonates

So, if TDS is the measure carbonates, magnesium etc.,. then GH and KH together should give some sort of indication of where the TDS lies?

Roan
 
Hannys_Papa said:
Seeing that noone really said anything in response to the point i brought up earlier (and without wanting to HJ this thread - sorry) - can i conclude that it doesnt matter if my tank water is high kH because it was brought up with crushed coral (as an example) and then i do a large waterchange with low kH tap water. This drop in TDS and pH wont cause any osmotic pressure and result in stress for the fish ?
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The KH won't change and Dave doesn't know why and no one else has answered the question "why" either.

Mine has gone from 2 to 4.5 dKH and stays pretty much at 4-4.5, no matter how big a water change I do.

Can't remember what thread I asked the very same question in :)

Great minds think alike!

Roan
 
RA-
1. Yes, but lots of other things as well in natural waters, even more in our tanks which are also relatively high in organics.

2. Yes, Ca++ and MG++ have nothing to do with pH.

3. Yes, and severely misunderstood in the hobby. Fish are sensitive to osmolarity.

4. Same as above. You can change the pH without significantly/detectably affecting the TDS - think about CO2 supplement.

5. Yes, also BW and estuarine fish.

6. Yes, but incomplete. We have processes going on in our tanks which do occur as such in the wild - the build-up of nitrogenous waste products and of organics is many-fold greater in captivity, and the biological processing of those and/or the chemical results of those are many-fold magnified in capitivity due to bioload issues (we have many-fold the biomass in out tanks as in natural waters). Don't expect straight high-quality (low TDS/high-resistance) RO water to support a tank. Supplements are needed. BTW, most but not all blackwater fish do fine in higher-TDS waters, but may not breed. Their egg membranes are harmed by Ca++ & Mg++.

7. Yes, but commonly suggested tank conditions may or may nor be the best for particular fish. Mollies for example are commonly suggested for NaCl-added tanks, but salt does not buffer the water upward, only adds TDS. Not all TDS is equal.

8. Yes.

9. Maybe. "Alkalinity" or buffering is better. The titration does not read just HCO3/CO3, but others as well. In the wild, it is primarily bicarbonate/carbonate. In tanks it can be a lot of other things as well, and can be affected by organic and inorganic acids present.

Not really, they are measures of only part of TDS. Sulfates, chlorides, sodium, potassium, etc. are common and do not read on GH or KH. GH/KH may provide hints that water is relatively hard or relatively soft, but concluding that to be the actual case is unjustified.

If you bring the tank water up with coral/aragonite/bicarb, and you replace it with large % volume partials with low TDS water (tap or RO), you most definitely do risk osmotic stress to the fish - a specialized case resembling OTS. Options include more frequent smaller percentage changes or pre-treating the replacement water. Water mods are rarely a fast, simple, or cheap process.
 
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