Low kH/gH, high pH - The Planted Tank Forum
 
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post #1 of 7 (permalink) Old 09-02-2015, 12:39 PM Thread Starter
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Low kH/gH, high pH

Hello,

I'm setting up a new planted aquarium (eventually with fish too) at a new home and trying to figure out what to do with my water parameters. All of our water that's accessible goes through a water softener, and, as one might expect, the waters tests at low kH (1 dKh) and no measurable gH (green immediately on the API test). The odd thing is that it also tests at a high pH -- it's off the scale of the normal pH test, meaning 7.6 or more. I need to pick up a high pH test to double check, but regardless, the pH is higher than I'd like it (I was hoping to keep Bolivian rams along with tetras and corydoras). 7 or so would be fine, but if it's around 8, that seems problematic at least for the rams.

We also have RO water, though doing water changes with that seems like it would be a pain (just a small spigot at our kitchen sink, so I'd have to wait forever to get 5-6 gallons for changing water in my 38-gallon tank). The RO water tests at a pH below 7 (around 6.5).

Obviously the first step is to test with a high-pH kit to see what I'm working with, but assuming pH is in the 8 range, how should I go about filling my tank and doing water changes? Equilibrium seems like a no-brainer for the gH (shoot for around 3-6 degrees?), and I suppose regularly dosing Flourish Excel will drop pH a little (right?). But I worry that using other products to get the pH down will be a headache given the low kH; swings and crashes worry me. Anyone have any success with products like Seachem Acid Buffer (which I suppose I'd have to use in conjunction with the Alkaline Buffer, since Acid Buffer says it works by converting kH, and I don't have much of that in my water)? Peat in the filter? Or, though not ideal (time wise), would it work to do water changes with RO water, add Equilibrium, and call it a day? Or do I need to buffer kH too? And wouldn't that raise pH pretty quickly?

Any help with any or all of this would be much appreciated, thanks... I've done a lot of reading on this stuff here and in other places, so I think I get the basics of how these parameters interact, but do let me know if I'm missing something.
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post #2 of 7 (permalink) Old 09-02-2015, 02:43 PM
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Drift wood, almond leaves, and/or injecting CO2?


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post #3 of 7 (permalink) Old 09-02-2015, 02:52 PM
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Originally Posted by end3r.P View Post
Hello,

I'm setting up a new planted aquarium (eventually with fish too) at a new home and trying to figure out what to do with my water parameters. All of our water that's accessible goes through a water softener, and, as one might expect, the waters tests at low kH (1 dKh) and no measurable gH (green immediately on the API test).
What kind of water softener do you have? Salt-regenerated ion exchange (the most common type, and if you are buying bags of salt, this is the kind you have).

Such softeners work by exchanging calcium and magnesium ions for sodium ions. Depending on how hard your water is coming in, this may result in quite a lot of sodium in the water (but not the chloride part, so your softener company will half-correctly tell you the salt doesn't go into the water). Regardless, high sodium levels aren't particularly desirable.

This process also should have no affect at all on the KH of your water, so the fact that the KH it is really low seems odd.

I'd also try letting your tap water sit out for a while and re-test the pH... Sometimes tap water is heavily depleted of CO2, and that temporarily raises the pH.. on exposure to air for a few hours it goes down.

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post #4 of 7 (permalink) Old 09-02-2015, 03:19 PM Thread Starter
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What kind of water softener do you have? Salt-regenerated ion exchange (the most common type, and if you are buying bags of salt, this is the kind you have).
Yes, it's a salt system.

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Such softeners work by exchanging calcium and magnesium ions for sodium ions. Depending on how hard your water is coming in, this may result in quite a lot of sodium in the water (but not the chloride part, so your softener company will half-correctly tell you the salt doesn't go into the water). Regardless, high sodium levels aren't particularly desirable.
Right, from what I've read, it's not ideal. As I understand it, the softener is replacing calcium and magnesium ions (not free floating, but bonded with something? this is where my lack of science background shows) with sodium ions, so it's not making salt water, but it is increasing the sodium content and taking away beneficial calcium and magnesium. I assume that the RO process that happens next (for my kitchen tap) removes the sodium issue? So maybe that's the fix for that issue, although it leaves me with an annoying water change process. Anyone that does RO, let me know if there's a way to do this more quickly than getting it from the slow tap that's typical of RO house systems. We're getting our water system serviced this week, so maybe I can ask the guy if there's a solution for that (maybe a second line from the RO tank that I can pump to the aquarium? out of my depth here).

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This process also should have no affect at all on the KH of your water, so the fact that the KH it is really low seems odd.
That's what I thought too; not sure what's going on there.

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I'd also try letting your tap water sit out for a while and re-test the pH... Sometimes tap water is heavily depleted of CO2, and that temporarily raises the pH.. on exposure to air for a few hours it goes down.
In process. I left some out this morning, so I'll check when I get home (will have high pH kit by then). I also put the water into my tank and let it sit overnight. Still high pH this morning. FYI, no fish or plants in there -- just a piece of driftwood and floramax capped with sand. (The driftwood appears relatively inert so far, not seeing any tannins yet, though maybe it's a slower process, and I haven't set up my filter yet, so water flow is nil).

If I go with RO water, it looks like Seachem Replenish may be the first step, and then a combo of Acid Buffer and Alkaline Buffer to achieve desired kH/pH balance?

I'm not super concerned about getting an exact pH -- more concerned with stability -- but a decent kH buffer and a pH in the 6.5 to 7.5 range seems like a reasonable goal.
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post #5 of 7 (permalink) Old 09-02-2015, 04:24 PM
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Yes, it's a salt system.

<snip>

Right, from what I've read, it's not ideal. As I understand it, the softener is replacing calcium and magnesium ions (not free floating, but bonded with something?
Generally the calcium and magnesium are from dissolved carbonates (ie: limestone), although sometimes sulfates (ie: gypsum) are involved...

That said, when dissolved in water, they really are almost completely free ions and not bonded to their original partner.

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I assume that the RO process that happens next (for my kitchen tap) removes the sodium issue?
Yes, although you'll want to re-mineralize the RO water before putting fish or plants in it.. pure RO can be rather rough on fish gills, due to osmotic pressure. Plants just for the most part just need the minerals as fertilizer...

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post #6 of 7 (permalink) Old 09-02-2015, 04:56 PM Thread Starter
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Drift wood, almond leaves, and/or injecting CO2?
Driftwood and almond leaves may lower pH, but I understand that they eat up kH too, which I don't have to spare. Ideally I'd like to get to a normal pH range while maintaining a kH buffer (around 3 dkH?). Maybe I could do that in conjunction with an alkaline buffer, though at that point I might as well use acid buffer directly rather than wait for driftwood or leaves to add in the tannins (at an uncertain rate).

BTW, what is "blackwater extract?" Just acid buffer with a more natural-sounding name? Or is there something else to it?

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Generally the calcium and magnesium are from dissolved carbonates (ie: limestone), although sometimes sulfates (ie: gypsum) are involved...

That said, when dissolved in water, they really are almost completely free ions and not bonded to their original partner.
Makes sense.

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Yes, although you'll want to re-mineralize the RO water before putting fish or plants in it.. pure RO can be rather rough on fish gills, due to osmotic pressure. Plants just for the most part just need the minerals as fertilizer...
Right. If I go the RO route, which I'm leaning towards despite the logistical hurdles, I'm thinking Seachem Replenish and then some combination of Acid and Alkaline Buffer to keep kH buffer and stable pH in a more normal range. Unless there's a better recommended mix of minerals.
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post #7 of 7 (permalink) Old 09-02-2015, 05:44 PM
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BTW, what is "blackwater extract?" Just acid buffer with a more natural-sounding name? Or is there something else to it?
There's a bit more to it, as it contains peat extract which contributes tannins to the water.


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Right. If I go the RO route, which I'm leaning towards despite the logistical hurdles, I'm thinking Seachem Replenish and then some combination of Acid and Alkaline Buffer to keep kH buffer and stable pH in a more normal range. Unless there's a better recommended mix of minerals.
So, I don't start with RO, but I raise the hardness and KH of my water to support Mollies (10+ dGH preferred)... I use equilibrium, but it can be a pain to get to dissolve.

Either should be fine unless you're doing shrimp.. there's whole dedicated products to boost GH for shrimp. (ie: Salty's)

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