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Discussion Starter · #1 · (Edited)
Hi guys,
After about 10 years out of the hobby, I have now moved to a new house with ample room for a nice fish tank. I'm planning on making a 600 liters (130 gallon) and looking for advice regarding my water parameters.
My water is coming from a deep well and test result came back as follow :

Ammonia : 0
Nitrate : 0
Nitrite : 0
Alkalinity : 236 mg/L (13,18 KH)
Hardness : 183 mg/L (10,22 GH)
Chlorides (Cl) : 4 mg/L
Conductivity : 508 μS/cm --> TDS : 325 PPM
Color : 5 UCV
pH : 6,82 UpH
Tannins-Lignins : 0,38 mg/L
Turbidity : 4,2 UTN
Calcium (Ca) 50,43 mg/L
Iron (Fe) : 0,44 mg/L
Magnésium (Mg) :13,84 mg/L
Manganèse (Mn) : 0,2490 mg/L
Sodium (Na) : 59,20 mg/L
mercury : 0mg/l
copper : 0mg/l
lead : 0 PPM
hydrogen sulfide : 0

I added an iron filter that changed some parameters :

Turbidity : 2,4 UTN (before 4.2UTN)
Iron (Fe) : 0,15 mg/L
Manganèse (Mn) : 0,0910 mg/L


It will be a heavily planted tank with CO2 and all the fancy stuff, and i'm planning on putting in there :
  • ramirezi
  • kuhli
  • betta
  • danios
  • tetras
  • Otocinclus
  • twig catfish
  • amano shrimp
  • red cherry shrimp


I will definitely add a water softener for the house and was thinking of getting a RO system for the tank and mixing the RO and softened water to get to something close to GH5 / KH5

My question is, what should i set the water softener to, and what % with RO mix should i do (considering all the other things in the water that will go in the tank after mix )?

Also, what do you think of using potassium instead of sodium for the water softener to limit the amount of sodium in the water after the RO mix, is it a good idea or is it useless... ?

And finally, what do you think of the species of fish ? do you think they would fit well together ? what do you think would be the best water parameter for all of them together ?

Don't hesitate to comment on anything, I'm still at the beginning of my project and I'm open to everything !! :)

PS : not native English speaker, i did my best.... :)
 

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Using the Potassium instead of the Sodium for the water softener sounds better. Or better yet, is there anyway you could run the well water through the RO unit without having it go through the water softener first? Otocinclus and Amano Shrimp like 6 dGH water in their tank. You could use some acid to further decrease the KH but the water has to sit for three days before putting it into the tank. Figuring out the right amount of acid to use can be tricky. Try to establish a better safe than sorry dose of the acid. I'm about to start experimenting with muriatic acid and CaCO3. Looks like you're going to be running a water treatment system. You might need a big water treatment tank for mixing and storage. Sounds exciting. Wish I had the space to do a big tank like that. Keep us informed. This is interesting.
 

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Discussion Starter · #3 ·
Yes you are right, there is no point mixing with softened water...
i think it will be Well water --> Iron filter --> RO system --> mix with iron filtered water.
and put the water softener on the side for the house. It will just be a little bit more plumbing :)
And i did not know about muriatic acid and CaCO3. i will look into it.
Do you think 6dGH is good for the other species to ? and what do you think dKH should be ?
 

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You will not have to use muriatic acid if you remineralize 100% RO water not mixing with the well water. Mixing well water with RO water you might use acid to reduce the KH a little because KH will still be high after mixing the waters 50/50. It's an unnecessary water processing headache I would avoid by using 100% RO water. 6 dGH should be good for everybody. It will help the shrimp molt. KH should be half of GH or lower. Having lower GH and KH is better for growing plants but then you would have to reassess your choice of stock. Paradoxically, otocinclus and shrimp like a higher GH which plants don't like as well. The consolation is that otocinclus and shrimp are effective at controlling algae.
 

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For determining what ratio to mix things in with RO, using this formula should make your life easier and will work for everything except pH.

C(desired) * V (desired) = C (well water) * V (well water) + C (RO water) * V (RO water)
C stands for concentration and V stands for Volume. For the purposes of this, just use % for the volumes rather than liters or gallons. You can assume that the RO concentrations are going to be very near or basically 0 for most things, but it looks like you've got tons of test kits so you could always check.

so if you wanted 90 mg/ L alkalinity, the equation would look like this:

90 * 100(%) = 236 *(V) + 0 * (100-V)
desired concentration * 100% (final volume) = well concentration * % well water + 0 from RO * 100- (Volume well water)

9,000 = 236V + 0
V= 38.13

So, to get that desired alkalinity of 90 mg/ L, you should use 38% well water and the rest (62%) RO.

Downside is, that's the correct % to get your desired alkalinity, but there's all the other parameters to worry about also and probably they won't be exactly 38%, so if you want exact perfect conditions, you're going to have to choose which one you get right through this method of mixing RO and which ones you're going to dose.

If RO concentration really is always 0 or very close to it, then you can just simplify the equation to:
C(desired) * V (desired) = C (well water) * V (well water)

pH is on a log scale and is so annoying to calculate that even chemists add bases and acids and bases to play guess and check till they get the correct pH for whatever solution they're making.
 

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Discussion Starter · #6 · (Edited)
Thank you Danold, that will be usefull.
My idea behind the water mixing was to make things "easier" because i will automate everything, including water change, but with a screw feeder and a scale it's not hard to add powder to the mix.
So if i do a water mix to get KH to 3, and use only supplement to increase the GH to 6 (2 times the KH), this way i still have some nutrient from the well water for plants/fish.
Using the formula, i would mix about 23% well water // 77% RO water to get 3 dKH, and that would give me about 2.35 dGH
For the supplement, i can use bee-shrimp-mineral-gh or equilibrium to raise the GH to 6.

What do you think ?
 

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Hey there, I agree. I'm not familiar with the shrimp mineral gH personally. I have equilibrium which I know has a great reputation. Following the instructions on the bottle for dosing always gets my water where the directions predict.
 

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I used to mix my very hard tap water with RO water in a 50/50 ratio to cut the hardness and it did work out well. So I think mixing can be a very viable option however as others have stated you have less control over your other parameters. Personally I didn't want to chase my water parameters and decided cutting the hardness in half was good enough for me but I can understand the desire to dial things in more.

When I used to do this I had my RO system plumbed in before the water softener as I had read that removing salt was hard on RO membranes so plumbing it prior to the softener would get you better life. However, I've recently been lurking on reef keeping forums (where they all use RO) and was reading that the opposite is true, that salt is easier for the membrane to remove and helps protect it so something to look into more possibly.

This next part is just speculation since I've never ran RO on a well so hopefully someone who has can chime in.

Luckily, since your on a well you won't have to worry about chlorine or choloramine which means there is a good chance your carbon block pre-filters will last longer and you might probably only need one. However, I would think about running two sediment filters before hand, one coarse and one fine since well water can have more particulates sometimes. Also, you might need to get a booster pump to ensure your getting adequate pressure since not all well pumps (or even city taps) can provide enough pressure for the best operation.
 
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