Ummmmmm Sulphur or in the case above sulphates

Do I win a prize Tom??

Great site and info by the way.

How would the sulfates react in water to produce an acid?

The same way sulphur applied to soil will lower the ph of that soil with the aid of bacteria and moisture to form sulphuric acid. it can take quite some time for this to happen though. Aluminium sulphate would lower the water alot quicker if it were used.

Tom,

(Please know that I am not criticizing GH Booster!)

That's the queer thing. Nothing in GH Booster, as far as I understand chemistry, should affect pH. Which is why I am scratching my head over this one. And at this point I do not at all recall what the water was like using Seachem's Equilibrium. I have not been scientific about it up to this point. No baseline. (I know, Tom, smacking my own hands...)

I'm fairly confident in the meter's readings, however, as my city's tap water is quite consistent, and the readings were pretty much as I remember them always being. From memory, typically just about pH 6.9 (+/- ~0.1) , TDS is something like 60 ppm (+/- 10), and conductivity (I think) was around 30-50. Sorry I'm not exact, but I'm away from home for the next couple of days. And when I saw the one planted tank was pH ~5.5, I immediately tested some tap water which had the readings I expected.

I have for awhile now just done the weekly 50% water changes from the tap on the planted tanks using the Python, then dechlorinated and added GH Booster and KNO3 + KH2PO4.

I have also for awhile been keeping a container of "aged", dechlorinated, tap water (20 gallons) and a sidekick small container (5 gallons) of "aged" dechlorinated tap water with 4g of GH Booster mixed in. As stated before, I use this sidekick mixture to combine with the "aged" straight tap water to "harden" as needed for my killie tanks. (By "aged" I simply mean the water has been in a container with a small pump for circulation and a heater and it has outgassed by the time I get around to using it.)

As it seems all tanks that have some water with GH Booster in it have gone quite acidic. I will see if I can get some pH 4.01 calibration fluid to use with the 7.01 to calibrate my meter upon my return home and test again.

• What the heck is my next step?
• Could I have a "bad" batch of GH Booster?
• Should I get some Equilibrium and test?
• Should I just add CaCO3 to offset this effect? If so, how much per n gallons of water?

-Jason

I don't know enough about chemistry to understand it, but perhaps with very large concentrations of SO4 in water, sulphuric acid is produced? I'm wondering if the GH booster was dosed without premixing and allowing it to sit at high concentrations, if there would be a difference. I dose magnesium sulfate and K2SO4 in my tanks and have never noticed a pH drop from the sulfates (and I have little to no buffer in my water). But I dose straight powder, and in small doses compared to what you added to your premix. I wonder if you were to take a quantity of water (aged) and dose what would be considered a "normal" amount assuming it was a tank, and test pH before and after, if there would be a difference? If not, something is happening in that premix that's not happening normally, or that wouldn't happen if you dosed straight powder.

I just did a little experiment of my own. I had three test tubes, filled them all with tap water (which for me is close to distilled, <5ppm of GH and KH and nothing else in great concentrations, according to my municipal water report) and added pH reagent. All of them came up at around 6.6 pH a light green which is normal for my tap water. I then added K2SO4 to one, Plantex CSM +B to the second, and KH2PO4 to the third. What do you think happened?

K2SO4 had no color change. The other two turned a bright yellow immediately, indicating a drastic pH drop.

Obviously, the concentrations of these things in the test tubes was far, far higher than you would ever have in a tank. But it makes me wonder what's happening chemically to cause this reaction, and what effect if any it would have on a tank's pH.

What is the KH of your tanks?

K2SO4, CaSO4 and MgSO4 should not alter pH.
Their by products may.........if they have any contaminants etc also.

Not that pH really has a lot of meaning since we add CO2 and are more concerned with KH and Ca and Mg.............

In soil, or where there might be strong reducing anaerobic conditions, SO4's=> H2S etc, but many acids can be produced under strong reduction.

In plain sterile tap, this should not be the case.
Most tap water is loaded with SO4.......

Regards,
Tom Barr

K2so4 should not alter ph but mgso4 can raise it and caco3 can in fact lower ph by the way of 'mopping up' hydrogen ions - no more, no less! There are a variety of ways to do this which can include calcium/lime - but it is certainly not limited to this.

Lime (CaCO3 - calcium carbonate) mops up hydrogen the following way:

CaCO3 + 2H+ → Ca2+ + H2O + CO2

But magnesium carbonate (with no calcium) can be just as effective:

MgCO3 + 2H+ → Mg2+ + H2O + CO2

Hydrogen is a highly reactive/aggressive cation capable of stripping other cations from their bonded anionic partners, e.g. (CO3)2-. Calcium, magnesium and other cations are merely passive passengers in the process of raising pH - it is their anionic partners that actually do the 'mopping up'.

Some unexpected results can occur though. For example, calcium sulphate (CaSO4) found in gypsum can react the following way in the presence of excess hydrogen:

CaSO4 + 2H+ → Ca2+ + H2SO4 + CO2

H2SO4 is sulphuric acid!! Therefore adding sulphate-based inputs (even with a calcium component) to acidic water can plummet pH levels down even further.


to adjust kh or alkalinity use bi-carb soda

to adjust gh and kh use calcium carbonate

Adding the salts alone I mentioned salts will not change the pH at equilibrium. If you add excess H+'s, well........of course that will change the pH, you are adding excess H+'s..........so the pH will move....

Yes, a small amount depending on how much H+'s you add will form H2SO4.
But not unless you add those H+'s.........

You can make the same exact argument for NaCl and adding H+'s.........CaCl2 + H2O + H+'s-> Ca+ HCL............

Add it and see.
Add NaCl.
Add KCl
MgCl2

Put another way, what happens if you add lime as Ca(OH)2 (basic) and H2SO4(acid)?

CaSO4 + 2H2O.........

HCL + NaOH = NaCl + H2O........
Strong acid + strong base to give neutral solution (H2O + salt)

pH of saturated CaSO4 solution is almost perfectly neutral (7.06). Same with MgSO4, except it's slightly acidic: look, here's the MSDS on it:

MAGNESIUM SULFATE
http://www.hillbrothers.com/msds/pdf...um-sulfate.pdf

pH is 6.5~7
Neutral which is what a typical neutral salt should produce.
magnesium + sulphuric acid ==> magnesium sulphate + hydrogen

Mg(s) + H2SO4(aq) ==> MgSO4(aq) + H2(g)
Sulphuric acid gives sulphate salt and hydrogen.

pH, ACIDS, BASES and SALTS Revision Notes for GCSE-IGCSE-KS4 courses at Doc Brown's Chemistry Clinic. for revising AQA OCR Edexcel CIE WJEC CCEA revising for science-chemistry exams-examinations docbacidsbasessalts)

I'm not quite sure where folks are getting mixed up here.
Too much google and not enough Chemistry I thinks.



Regards,
Tom Barr

I'm not a chemistry buff whatsoever, but I try to learn... this is probably oversimplifying it but I have to start somewhere.

So if there are extra H+ kicking around anyway, isn't the water already by definition acidic? Would the reaction of the excess H+ with the other things somehow make the water more acidic than it already was before? If so, don't more H+'s have to be coming from somewhere? How can more H+ be around to lower pH if we don't add any more H? Is this what you're saying Tom?

In my little experiment, the KH2PO4 made the water more acidic. I see an H there in the equation so this must have ultimately caused it in some way, right? The Plantex CSM+B did too, but I don't know the ingredients of this. The K2SO4 did nothing....because I wasn't adding any H? My understanding of this is far from complete....it's been way too long since chemistry class.