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Aerate RO water or not?
- Thread starter Zeeto
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AverageWhiteBloke
Member
I'm not 100% on this but I think I read somewhere that R.O water before it is re-mineralised absorbs co2 from the atmosphere which is why it is very acidic. I don't suppose there would be much point in aerating it if it is to stand in the water but for a while. I could see a point in it before adding it to the tank but if it's had the salts added it should buffer itself up fairly quickly.
Or you could wait for someone much better qualified to answer this is just a guess on my behalf
Or you could wait for someone much better qualified to answer this is just a guess on my behalf
tomsteer
Member
I know that it used to be an option to aerate water to remove chlorine before adding it to a tank.
I don't think there is much need to aerate RO water, especially if you keep it in an air-tight container.
Cheers,
Tom
I don't think there is much need to aerate RO water, especially if you keep it in an air-tight container.
Cheers,
Tom
a1Matt said:
Hi,
I find that quite alarming Matt, I have always been under the impression that neat RO water isn't healthy for the fish due to poor osmo-regulation properties.
I also heat the water prior to water changes (unless of course its warm enough at room temp like it is now) but no longer bother to airate it, my fish cope fine with it but then I currently have a small bio load on the tank if I witnessed the fish gasping after water changes I'd rethink my strategy.
Regards, Chris.
Hi all,
The aeration won't make any difference to the pH, the reason the water is acid is that it has no buffering, so even the small addition of H+ ions (from CO2 + H2O ⇌ H2CO3 in solution as H2CO3 ⇌ HCO3− + H+) will cause the pH to decline to very low levels.
Once you add some carbonate buffering (dKH) this doesn't happen.
CaCO3(solid) + H2CO3(aq. in solution) ⇋ Ca2+(aq) + 2HCO3-(aq) (exactly same for Mg2+ as well, so both Ca and Mg are usually added together and expressed just as calcium).
A lot of Apistogramma and wild Discus keepers use 100% R.O. and just peat filter it before use, this is pretty close to the water in the Rio Negro etc. which has no detectable hardness and electrical conductivities below 20 microS. you couldn't do this if you add CO2 and the pH will be inherently unstable, which is why it is suggested buffering the R.O. water to 4dKH.
Unless you keep extreme black water fish there is no real reason advantage in having very low buffering.
cheers Darrel
Is basically correct, as long as the water is not always in sealed air tight containers it will pick up atmospheric oxygen and CO2 until it is at equilibrium with the atmosphere. Pure H2O (H+ & OH-) contains no solutes, so it has no chemical or biological oxygen demand, and therefore no processes that utilise the dissolved oxygen in the water.
The aeration won't make any difference to the pH, the reason the water is acid is that it has no buffering, so even the small addition of H+ ions (from CO2 + H2O ⇌ H2CO3 in solution as H2CO3 ⇌ HCO3− + H+) will cause the pH to decline to very low levels.
Once you add some carbonate buffering (dKH) this doesn't happen.
CaCO3(solid) + H2CO3(aq. in solution) ⇋ Ca2+(aq) + 2HCO3-(aq) (exactly same for Mg2+ as well, so both Ca and Mg are usually added together and expressed just as calcium).
A lot of Apistogramma and wild Discus keepers use 100% R.O. and just peat filter it before use, this is pretty close to the water in the Rio Negro etc. which has no detectable hardness and electrical conductivities below 20 microS. you couldn't do this if you add CO2 and the pH will be inherently unstable, which is why it is suggested buffering the R.O. water to 4dKH.
Unless you keep extreme black water fish there is no real reason advantage in having very low buffering.
cheers Darrel
a1Matt said:
chris1004 said:
dw1305 said:
I agree with both Chris and Darrel.
Luckily I do keep extreme blackwater fish!
Both my chocolate gouramies and my boraras brigittae all thrive with the low TDS\GH\KH.
(my TDS hovers around 75ppm, KH 0, GH 0).
If it were not for the chocolate gouramies I would just use London tap water.
AverageWhiteBloke
Member
I was going to mention the Osmoregulation thing with fish but wasn't confident enough I also always thought that pure water and fish didn't mix, if a fish is kept in water of the wrong mineralisation i.e soft water fish in very hard water that the fish can get weakened by it's body trying to regulate it's salt content with water it has not adapted to live in.
If the water is totally devoid of minerals even soft water fish may not be happy.
Like I said though far more experienced people here.
I also always thought that pure water and fish didn't mix, if a fish is kept in water of the wrong mineralisation i.e soft water fish in very hard water that the fish can get weakened by it's body trying to regulate it's salt content with water it has not adapted to live in. If the water is totally devoid of minerals even soft water fish may not be happy.
Like I said though far more experienced people here.
Hi all,
As a general rule carbonate rich water support a lot more in the way of invertebrate biodiversity, so grow a bigger range of larger fish. If you take a large lake like Lake Tanganyika it is almost as stable as the sea, it has an immense volume of very highly buffered warm water and has existed as a lake for a huge amount of time. The fish have evolved in a stable environment and have very little tolerance of any other condition, they have also evolved to fill very small specialised niches.
Soft water "Black water" fish will usually have more tolerance of changing conditions, but the extremely acidic nature of their environment drastically reduces bacterial activity, and they may be prone to bacterial infections etc when kept in harder water, there may also be problems with egg shell hardening etc. A further potential problem is that they also tend to be opportunistic feeders, eating anything and everything, often leading to problems like bloat. As a general rule acidic water hold much less biomass than more base rich ones, although exceptions may occur in exceptional conditions (the igarapes and flooded forest of the Amazon basin for example).
cheers Darrel
I think that the problems with very soft water depend upon the fish, but it is definitely best to keep hard-water fish in hard water etc., but I'm not sure how much of this is to do with osmo-regulation. You can think of a fish like a Brown Trout (Salmo trutta) which is happy in a full range of salinities from salt to fresh, and a range of carbonate hardness levels from 0 dKH through to water that is fully saturated with calcium carbonate, the critical requirement for trout in any water is a high level of dissolved oxygen. Acididfication has killed many trout fisheries, but this is mainly to do with the toxic effects of soluble aluminium ions etc on invertebrates and fish eggs rather than the acid water itself.
As a general rule carbonate rich water support a lot more in the way of invertebrate biodiversity, so grow a bigger range of larger fish. If you take a large lake like Lake Tanganyika it is almost as stable as the sea, it has an immense volume of very highly buffered warm water and has existed as a lake for a huge amount of time. The fish have evolved in a stable environment and have very little tolerance of any other condition, they have also evolved to fill very small specialised niches.
Soft water "Black water" fish will usually have more tolerance of changing conditions, but the extremely acidic nature of their environment drastically reduces bacterial activity, and they may be prone to bacterial infections etc when kept in harder water, there may also be problems with egg shell hardening etc. A further potential problem is that they also tend to be opportunistic feeders, eating anything and everything, often leading to problems like bloat. As a general rule acidic water hold much less biomass than more base rich ones, although exceptions may occur in exceptional conditions (the igarapes and flooded forest of the Amazon basin for example).
cheers Darrel
Hi,
Ditto that mate.
I do understand kind of why you think it would be of benefit to use pure RO water but I have to question the logic behind that decision.
Because I also use 100% RO water but remineralised I know just how easy it is to achieve a predetermined level of both KH and GH and cannot for the life of me understand why anyone would want to run a tank with zero buffering from the KH. I know it can be done but I fail to see the advantage of removing the safety net completely. I run my planted tank with a KH of 1 now and it is child's play to remineralise to this level or indeed to increase to whatever level I want and its very very cheap to do so. Check out James's planted tank website and his recipe and alter the quantities from there to suit although I'll admit I have found it to be perfect the way it is.
As for the GH we know its made up of predominantly magnesium and calcium both of which are required by plants in order to flourish so why on earth would a zero level of either be beneficial in a planted tank? again its easy and cheap to achieve whatever water parametres you want and I run my softwater tank with a GH of 4-5 which would be low enough to keep any 'blackwater' fish happy but it would be just as simple for me to lower it even further if I felt the need.
When it comes to Osmoregulation all you have to do is to google that word and a plethora of information becomes available to you ALL of which states its importance for the long term health of the fish.
Now I'm no chemist or scientist and much of it goes way over my head but I can't see the logic of running a tank without any of the elements that at worst won't do any harm in small quantities and at best are essential for good health.
Hopefully someone else who does understand more deeply will chime in.
Regards, Chris.
a1Matt said:
Ditto that mate.
I do understand kind of why you think it would be of benefit to use pure RO water but I have to question the logic behind that decision.
Because I also use 100% RO water but remineralised I know just how easy it is to achieve a predetermined level of both KH and GH and cannot for the life of me understand why anyone would want to run a tank with zero buffering from the KH. I know it can be done but I fail to see the advantage of removing the safety net completely. I run my planted tank with a KH of 1 now and it is child's play to remineralise to this level or indeed to increase to whatever level I want and its very very cheap to do so. Check out James's planted tank website and his recipe and alter the quantities from there to suit although I'll admit I have found it to be perfect the way it is.
As for the GH we know its made up of predominantly magnesium and calcium both of which are required by plants in order to flourish so why on earth would a zero level of either be beneficial in a planted tank? again its easy and cheap to achieve whatever water parametres you want and I run my softwater tank with a GH of 4-5 which would be low enough to keep any 'blackwater' fish happy but it would be just as simple for me to lower it even further if I felt the need.
When it comes to Osmoregulation all you have to do is to google that word and a plethora of information becomes available to you ALL of which states its importance for the long term health of the fish.
Now I'm no chemist or scientist and much of it goes way over my head but I can't see the logic of running a tank without any of the elements that at worst won't do any harm in small quantities and at best are essential for good health.
Hopefully someone else who does understand more deeply will chime in.
Regards, Chris.
AverageWhiteBloke
Member
The water I have in my tap has very little mineral content not even registering on a standard test kit but I'm going back to de-io because of other nasties in there. I simply add a level tspoon of JBL Aquadur to a 5gal fermenting bin to give me 3dkh suitable for my shrimp.
The old API purifier I have actually advises not mixing the pure water with fish but doesn't explain the reasoning why. Pure water is unstable and can cause chemical reactions not usually associated with buffered water which is why I don't put it directly into my tank unless just topping up from evaporation.
I've seen posts on this board about how very soft water is worse than medium for the plants and with the minerals needed for growth completely taking them out can't be good? Perhaps the people who are using pure water for changes are adding them back in with their dosing regime or possible gravel or rocks in the tank that harden water I don't know.
When I kept discus with no plants I still added minerals then as the ones I had were generally shop varieties or locally bred fish which would never have been in so pure water. Wild or F1 might have been a different story in acclimatising for sale but the couple of discus breeders I know raise their fry in harder water for better growth so there is that aspect where does too soft water slow growth? They seem to think so and only breed in vsoft water for the eggs.
The old API purifier I have actually advises not mixing the pure water with fish but doesn't explain the reasoning why. Pure water is unstable and can cause chemical reactions not usually associated with buffered water which is why I don't put it directly into my tank unless just topping up from evaporation.
I've seen posts on this board about how very soft water is worse than medium for the plants and with the minerals needed for growth completely taking them out can't be good? Perhaps the people who are using pure water for changes are adding them back in with their dosing regime or possible gravel or rocks in the tank that harden water I don't know.
When I kept discus with no plants I still added minerals then as the ones I had were generally shop varieties or locally bred fish which would never have been in so pure water. Wild or F1 might have been a different story in acclimatising for sale but the couple of discus breeders I know raise their fry in harder water for better growth so there is that aspect where does too soft water slow growth? They seem to think so and only breed in vsoft water for the eggs.
Hi all,
These are the figures for the lower Rio Negro (from Mayland & Bork, "S. American Dwarf Cichlids"). These waters either have no plants or an extremely limited very slow growing flora because of the extreme conditions. It also says in the book "as the river is very poor in nutrients and therefore has almost no insect larvae, and an the absence of mosquitoes makes the stay a pleasure"
electrical conductivity - 11microS
carbonate hardness - 0.3 dKH
total alkalis Ca2+, Mg2+ - 0.02 dGH
nitrate mg/l - <1
Some of the problems with keeping (and particularly breeding) some Apistogramma, Matt's Chocolate Gourami etc. is that they have very little resistance to normal bacterial communities, because they are adapted to these almost sterile (in all meanings of the word) environments.
cheers Darrel
This is all true, the only reason for having extremely soft low conductivity water would be to keep and breed fish from acid, extremely cation and nutrient poor waters.
These are the figures for the lower Rio Negro (from Mayland & Bork, "S. American Dwarf Cichlids"). These waters either have no plants or an extremely limited very slow growing flora because of the extreme conditions. It also says in the book "as the river is very poor in nutrients and therefore has almost no insect larvae, and an the absence of mosquitoes makes the stay a pleasure"
electrical conductivity - 11microS
carbonate hardness - 0.3 dKH
total alkalis Ca2+, Mg2+ - 0.02 dGH
nitrate mg/l - <1
Some of the problems with keeping (and particularly breeding) some Apistogramma, Matt's Chocolate Gourami etc. is that they have very little resistance to normal bacterial communities, because they are adapted to these almost sterile (in all meanings of the word) environments.
cheers Darrel
Hi,
Thanks Darrel that's fascinating, I was assuming, probably wrongly, that Matt was using pure RO water for water changes on his planted tank.
I don't suppose I could be a bit cheeky mate and ask you (Darrel) for a quick explanation of osmo-regulation for dummies i.e. me, and what it means to us as aquarists and the fish that we choose to keep.
Regards, Chris.
Thanks Darrel that's fascinating, I was assuming, probably wrongly, that Matt was using pure RO water for water changes on his planted tank.
I don't suppose I could be a bit cheeky mate and ask you (Darrel) for a quick explanation of osmo-regulation for dummies i.e. me, and what it means to us as aquarists and the fish that we choose to keep.
Regards, Chris.
Actually your assumptions were pretty good!
I do the water changes for the gouramies, but the tank is also planted.
It is a low light tank with only crypts, swords, anubias and mosses and they can all withstand the nutrient deprivation (they just grow very slowly).
Although the WC are pure RO, and most of the plant nutrients come from fish waste, I do dose the occasional dry salts (gypsum, epsom salts, n, p, k, and trace) in small amounts to keep the plants ticking over. It is trickier to keep them healthy than with pressurised co2 and EI, but I have a good balance and am happy that the tank is stable and in good health.
Enough of my tank, lets get back to learning the good stuff from Darrel
I do the water changes for the gouramies, but the tank is also planted.
It is a low light tank with only crypts, swords, anubias and mosses and they can all withstand the nutrient deprivation (they just grow very slowly).
Although the WC are pure RO, and most of the plant nutrients come from fish waste, I do dose the occasional dry salts (gypsum, epsom salts, n, p, k, and trace) in small amounts to keep the plants ticking over. It is trickier to keep them healthy than with pressurised co2 and EI, but I have a good balance and am happy that the tank is stable and in good health.
Enough of my tank, lets get back to learning the good stuff from Darrel
AverageWhiteBloke
Member
The way I understand osmo-regulation is a bit like your drop checker, once in the water the indicator fluid, the air trapped between and your tank water all go into equilibrium i.e same amount of co2 in them all. This is the same with fish if a fish is for example a soft water species then the salts/minerals in the fish will try and equal up with the surrounding water. If the water has the wrong mineral content then the fish the fish will use up energy trying to reach equilibrium with the water although probably only in extremish circumstances. A fish is a bit like a reverse osmosis unit where the fish is the permeable membrane. Summary fish in wrong water using energy to keep in balance=weakened fish.
The commoner variety fish are used to living in water of varying hardness but fish like chocolate gourami, discus wild versions are sensitive to this. The eggs are also which is why people use no hardness water that were discussing for breeding purposes but is probably better to have some buffering when maintaining a long term set up like most of us have.
Or something like that I'm not very good at explaining stuff.
The commoner variety fish are used to living in water of varying hardness but fish like chocolate gourami, discus wild versions are sensitive to this. The eggs are also which is why people use no hardness water that were discussing for breeding purposes but is probably better to have some buffering when maintaining a long term set up like most of us have.
Or something like that
I'm not very good at explaining stuff.
AverageWhiteBloke
Member
http://en.wikipedia.org/wiki/Osmoregulation Like I was saying just better explained As you can see a soft water fish in hard water would have a hard time keeping in equilibrium. Its a long the lines of us going into shock by losing too many fluid or salts through sweating which we need to replace. If a hard water fish is in soft water the pressure will try to even up and in effect suck salts from the fish. So the closer the mineral content of the water is to what the fish has evolved to live in the less energy it uses trying to live there.
Or words to that effect
As you can see a soft water fish in hard water would have a hard time keeping in equilibrium. Its a long the lines of us going into shock by losing too many fluid or salts through sweating which we need to replace. If a hard water fish is in soft water the pressure will try to even up and in effect suck salts from the fish. So the closer the mineral content of the water is to what the fish has evolved to live in the less energy it uses trying to live there.Or words to that effect
