New Setup Tap & Or Ro Water

[Coys55]

I'm returning to tropical freshwater fish keeping after a 40 year break; things seem to have got a lot more technical since the early 1970's!
 
My setup will be a 240 litre Eheim aquarium and Eheim Pro 3 2073 external filter, which I intend to stock mainly with tetras, which of course prefer soft acid water and natural plants.
 
I live in Basildon, Essex, and my tap water is high pH (I can't find any figures online and wioll check once my pH kit arrives, but suspect it is well over 8, and with hardness in the 99-130 mg/ Ca range (hard to very hard). I do have a domestic water softener, but I understand that this type of softened water is not suitable for fish anyway, but I also have an outside tap, which is mains-connected.
 
I understand that pH buffering will not lower then pH significantly with very hard water, and I would still be stuck with the hardness anyway, so I considered purchasing a small RO unit to generate my own softened water, but I understand that wastage is 85-90% and the process is very slow so rejected that option. Another option is my local supplier, who has offered to supply RO water at what appears to be a reasonable price.
 
So finally to a question; should I go for 100% RO water, or a mix of my own tap water plus some RO. And if a mix, how much?
 
 

 

[Byron]

I would aim to use a mix, as some mineral will be fine (if plants are intended, and presumably with tetras they would be, this will be helpful for the plants).  And it will lessen the expense/waste of RO if less can suffice.  Depending upon what fish species, you may not have to do too much.  Another option is rainwater, which is soft and usually acidic.  Generally speaking, the GH/KH of the tap water will be proportionally reduced according to the mix with "pure" water; for example, if the GH is 20, mixing it half/half with RO would result in a GH of 10.
 
See if you can ascertain the GH (general hardness) from the water supplier; many have a website with data posted.  Also the KH (carbonate hardness, or alkalinity) which is your pH buffering agent.
 
You are correct about water softeners; these frequently use sodium salts to replace the hard mineral salts, which does lower the GH but the sodium is in many ways far worse for the fish.
 
Byron.

 

[DrRob]

You do indeed have hard water in Basildon according to the suppliers site. They don't publish the KH online, just the GH, but if you ask them they'll send you a break down of what they have in the water.
 
Many of us have struggled with rain water in the UK, the air quality isn't terribly good up there and things do get dissolved in it, but worse than that is the residue that ends up on the collection surfaces (your roof) ranging from bird droppings, through dead animals and leaves, to crop spray and road fumes. Those in the more rural areas, and particularly in the South West with the prevailing winds coming in from the Atlantic, have had better experiences. If you go down this route then have a think about things like a daphnia toxicity test, it's a simple method of add a daphnia culture to the water to be added to the tank before doing the change. They're quite sensitive, so if they die, don't use it, if they don't then you have live food in the water change.
 
Do remember that we rely on stability of water to keep our stock healthy, so whatever you intend to do you need to be willing to continue to do for the long term. With some exceptions most fish would prefer to be in slightly the wrong water than to have the conditions changing around them. I'm generally an advocate of not messing with the water that you have but working with it and stocking what will do well in your supply, it keeps things simple in the long run and the unforeseen need for a large water change becomes far easier if you can do it from the tap rather than relying on an external supply. There will be a great selection of fish available that can do really well in hard water.
 
At the risk of sounding slightly hypocritical at this point, I do use RO. My reason is slightly different though, as I have barely legal water for ammonia and nitrate due to local farm run off. Byron is entirely correct in the method of cutting, RO, should, in theory, be pure with a KH and GH of 0. They're linear scales, so the maths is quite simple, 50/50 will halve the levels, 25 tap with 75 RO will quarter them and so on. The alternative option that opens up is to get very involved with the chemistry and to use 100% RO and to add chemicals back in to the mix. This removes any unknowns from the water and gives you even more control over what is going on, however the risk is that you might miss a few minor essential elements (and, as Byron pointed out, it's more expensive in water), depending on what you're using, and that you still need to keep up what you're doing. I used Seachem Equilibrium for this for a while, before I moved to home made mixes as they work out a lot cheaper (and I can source the chemicals very cheaply through work) but it does require some homework and maths.

 

[Coys55]

Depending upon what fish species, you may not have to do too much. 

 
Thanks for the advice Byron & DrRob. I think I'll try a 50/50 mix of RO and tap water and then monitor the pH and hardness.
 
Regarding species, (water permitting) I intend stocking with Congo, Neon (or Cardinal) and Emperor Tetras. I'm sorry to say that most of the hard water fish that I'm aware of don't really appeal to me.

 

[Byron]

 

Depending upon what fish species, you may not have to do too much. 

 
Thanks for the advice Byron & DrRob. I think I'll try a 50/50 mix of RO and tap water and then monitor the pH and hardness.
 
Regarding species, (water permitting) I intend stocking with Congo, Neon (or Cardinal) and Emperor Tetras. I'm sorry to say that most of the hard water fish that I'm aware of don't really appeal to me.
 

 
The Congo and Emperor should be fine with moderate hardness.  The neon and cardinal are less adaptable and while they may manage for a time I believe they would have issues in the long run.  By "moderate" I mean with a GH no higher than about 12 dGH (210 ppm); we don't know the GH here yet, so this may or may not require much mixing.
 
The other thing about the combination is their different manners.  Neons and cardinals are very sedate fish, not active swimmers, whereas the Congo and Emperor are more the opposite.  Consider a species level of activity when looking for other possibles.  And both the Congo and Emperor are mid-water level, generally, so consider upper-level and lower-level (substrate) species as well to balance out.
 
Byron.

 

[Coys55]

Thanks again for the advice Byron; I must admit that I wasn't thinking about species for different levels, apart from a few Corys for the substrate.
 
In between writing my previous post and your recent post I did some research and agree that Cardinals are almost certainly out; there is no way I can get the pH and dGH down to acceptable levels without 75-100% RO, which I'm not going to do. If I can get the dGH down to 8ish and the pH down to the low 7's then I think that most of my preferred species should be fine..

 

[Coys55]

It's been almost six months since setting up my aquarium, so I thought I'd give a progress update.
 
As discussed I started with a 50/50 RO/Tap mix. Kh was 5, Gh 9 and Ph >8.0. Since then I've done a weekly water change with 50 litres of RO plus 6-12 litres of warmed tap water (depending on how cold the RO was). Kh is now 3, Gh 7 and Ph aound 7.6.
 
I had a couple of algae issues; firstly black beard, whch eventually went on its own, followed by a horrible blue-green episode, which covered everthing; plants, gravel, rocks, the lot. After several attempts at clearing it manually and not being too keen on introducing chemicals, I eventually devided I had to do something and bought a tube of Ultralife Blue Green Slime Stain remover from Amazon and it really did the trick; two treatments 48 hours apart and it just fell off the plants and gravel.
 
I went with my original plan for small shoals of Congos, Emperors and Cardinals and added a small group of Panda Corys. As it happens the Cardinals stick mainly to the bottom half and the Congos to the top half, with the Emperors sometimes shoaling and at other times just hanging around their favourite plants on their own or in a pair. All seem quite happy together.
 
Plants are growing like crazy; yesterday I did some tidying and cleared out an enormous amount of Vallis and replaced two pieces of lava rock with two pieces of driftwood.
 
I'll add a couple of photos next.

 

[Coys55]

 

[Byron]

It is nice to hear things worked out.  My only suggestion now would be some floating plants.  The fish will thank you, and reward you with even nicer colour.
 
Byron.

 

[Coys55]

It is nice to hear things worked out.  My only suggestion now would be some floating plants.  The fish will thank you, and reward you with even nicer colour.
 
Byron.

Thanks for the advice. I'll give it a try, but I reckon they will end up in one corner; that Eheim creates a VERY strong current on the surface.
 
I forgot to mention the Siamese algae eaters; they are crazy, never stop eating and keep all the plants clean of hair algae. I've also got a population of assasin snails; I bought three for my son's aquarium because he had a massive snail infestation and boarded them in my aquarium for about a week before he took them. During that time one of them must have laid eggs because I've now got at least five of them, probably more. The original three cleared his aquarium in about a week!