RO - Is It Really Necessary?

Can someone explain how us long time fish people  managed not to lose very many fish before Reverse Osmosis was decided to be the be all and end all of fish keeping !!

Much to the delight of the equipment manufacturers 

Like Sues post in your other thread RO is used when people want to keep fish which dont automatically suit their water characteristics.

Another use for RO is where tap water has nitrate so high it is almost at the legal limit of 50 ppm. RO is used to reduce the amount of nitrate, but depending on the fish, their hardness needs and the hardness of the RO/tap water mixture, some remineralisation salts may have to be added. Recent research shows that fish do not live to their natural life span in water that has over 20 ppm nitrate.

RO is not the be all and end all of modern fish keeping. In fact I advise against using it as it does have its drawbacks. If RO water is used, there is the expense of buying it, or the equipment and the water it wastes if the fish keeper is on a water meter. The exact ratio of tap:RO water must be used at every water change, or exactly the same amount of remineralisation salts added to the new water. An emergency water change with all tap water can never be done or that would harm the fish as much as not doing a water change.
It is much better to keep fish that have evolved in the same hardness as our tap water rather that alter our tap water to suit a particular fish. I would love to keep shell dwellers. But I have soft water so that would mean adding Rift Lake salts to the new water at every water change. So I keep soft water fish.

Nowadays we have a lot more fish species than there once were. Certainly more than when I first had fish 20 years ago. And the fish that were once hardy tend to be more delicate now. Fish breeding is big business. Commercially bred fish are kept in very poor conditions, and breeders use any fish rather than good breeding stock. This results in weaker fish being offered for sale. The classic example of this is dwarf gouramis. So many of the gouramis bred in the far east are infected with dwarf gourami iridovirus and these die within a few months of purchase.
More wild caught fish are available now, and these will suffer more than commercially raised fish if kept in the 'wrong' water conditions.
And highly inbred fish like guppies are also harder to keep alive.




And of course the saying that surviving is not the same thing as thriving also applies to our fish.

What is your tap water hardness @Madtony? Try looking on your water suppliers website if your not sure.
How does this compare to the needs of your angelfish? Try a site like seriouslyfish.com if unsure.

In the  wild shell dwellers live in sandy areas complete with lots of shells to hide in. They also live in naturally hard water.
Now thats not to say they cannot live on gravel with caves, its just not their natural environment. Your tank sounds like a case in point.

It does concern me that your tap water may be in a hardness range outside that of that which your fish can cope with.  Hardness has been shown to affect fishes osmoregulation.  Like we all learnt in school osmosis is two different liquids moving through a barrier to equalise their differences. Fish live in water and so have to regulate this process to maintain their bodily fluids.  All fish have a range of hardness values in which they can operate and whilst being in water outside this range will not lead to a rapid demise (as it would putting a freshwater fish in salt water for example) it does increase the level of stress on the fish and can lead to premature death either because the fish is having to work so hard to stay alive or eventually it can lead to internal organ failure for similar reasons.  The fish would likely look fairly normal but have a reduced lifespan. http://www.fishdoc.co.uk/water/osmoregulation.html

Many fishkeepers try to provide as natural environment as they can for their fish to ensure they are as happy and healthy as can be. Multicoloured gravel and ship ornaments remain though and don't necessarily mean unhealthy fish... they are just not suitable for all fish. Water hardness requirements are newer to the hobby but as our understanding of them grows they are showing themselves to be vital to long term fish health.

Hope that helps 

Commercially raised fish can cope with conditions outside those that would harm their wild ancestors but this cannot be taken to extreme. Take mollies as an example. These fish have been commercially bred for countless generations yet put them in soft water and they get a condition called the shimmies.

We must also bear in mind that a lot of the less common fish and the hard to breed fish are wild caught and these fish must have water close to their natural habitat.



The main mineral in hard water is calcium, with some magnesium and trace amounts of other metals.
Soft water fish have evolved in water that contains few minerals. Their bodies have evolved to retain minerals as there are few in the water. Put a soft water fish in hard water and their bodies retain too many minerals so that it fills their their organs with calcium. This does not kill them instantly but it does shorten their lives.
Hard water fish have evolved so that their bodies excrete minerals to stop all those minerals in their water clogging their organs. Put hard water fish in soft water and they still excrete those minerals - but the soft water they are now in can't replace them. So the minerals in their bodies become depleted which does harm them, and quicker than keeping soft water fish in hard water.

Think of the hardness scale as very soft, soft, moderately soft, moderately hard, hard, very hard.
A wild fish that evolved in very soft water would probably be OK in soft, and a commercially bred descendant in moderately soft, but even a commercially bred, very soft water fish would suffer in moderately hard water.