Has 'soil' lowered my pH so dramatically?

[On_a_dishy]

I have read on the forum that soil can lower pH - could it have done this by this much?
My tap water is hard - so hard that I started the process of introducing RO water to support by beautiful betta. At the same time I decided to plant my tank, and, having had had a really good experience with Flora Pro in the past, put that in, topped with gravel.
My pH was originally between 7.5 and 8, the GH was 180 (at least), and the KH was between 120 and 180. I then did my landscaping and current readings (which use some different measurements as I now use an eSHa kit) are:
34L tank
pH 6.4 (or less - this is the lowest reading available and I'm worried it's even lower)
KH 6
GH >14
Nitrites less than 1 (I'm at the end of cycling - they'll soon be 0)
Nitrates between 10 and 25
I phased out the RO water - which I'd only just started introducing anyway - 2 weeks ago. I want to get a snail but with the pH that low I think the shell will struggle.
Is soil responsible for this drop?

 

[GaryE]

I have lowered the hardness of water using large volumes of peat and spaghnum moss. So if you are reducing hardness, pH will follow most of the time. Before I was aware of the ecological issues with peat, I used a lot. I would fill a 20 gallon tub half full of soaked peat, and my 140ppm tap would be at 80ppm fairly quickly. It's a messy method, but it worked.

Peat would change hardness and add tannins for months.

 

[gwand]

I have lowered the hardness of water using large volumes of peat and spaghnum moss. So if you are reducing hardness, pH will follow most of the time. Before I was aware of the ecological issues with peat, I used a lot. I would fill a 20 gallon tub half full of soaked peat, and my 140ppm tap would be at 80ppm fairly quickly. It's a messy method, but it worked.

Peat would change hardness and add tannins for months.

Do Indian almond leaves work To lower pH? I read that but wasn’t sure if it was true.

 

[GaryE]

pH is unimportant, to me. It is an indicator of water hardness, which is crucial. I have soft tapwater so I can make use of almond or oak leaves to add tannins to the water, and that will add to the environment I want to have for a lot of rainforest fish. But I'd argue that lowering the pH temporarily with botanicals does very little. They are best used when the water hardness is already where you want it, and you want tannins in there.

I used to breed Apistogramma veijita, and if I wanted a spawn in my already appropriate water hardness, I would add tannins. They would always spawn the next morning. No tannins as triggers, and I could wait a very long time for fry. So they can be very useful.

 

[TwoTankAmin]

I am preety sure what you are seiing is the result of combining the RO water with cycling. In a tank KH, aka temporary hardness, comes from carbonates and bicarbonates. These are forms of inorganic carbon as is CO2. Who uses these things in our tanks? The answer is plants, algae and the bacteria which keep the tank cycled in part ot completely.

Pure water essentially has 0 KH and should be neutral pH. RO without DI (deinonization as well) is not quite pure. But I think your set-up needs a KH boost if you want the pH back up some.

You can do this nt adding a bag of crushed coral or similar form of calcium carbinate (aragonite, limestone, seashells etc.). This will react with an acid pH and dissolve in the water which add carbonates. If you were doing a rift lake tanks you could use nbaking soda, sodium bicarbonate. But this adds sodium to the water and tends to drive the pH towards and equilibrium of 8.2. Safe for rifties not for many other fish especailly softer water ones.

If your fish are having issues with nitrite a small amount of salt will fix that and you do not need to do a water change. Dosing info for this can be found here https://www.fishforums.net/threads/rescuing-a-fish-in-cycle-gone-wild-part-il.433778/

I have one tank I run for fish which star at pH 4.2 and end up at 6.0 in the end. I use RO/Di water and digital test equipmeent and I g=have to pre-mix changing water accordingly. I also wat staained water and I do all of this using the following:
RO/DI unit.
Mutiatic acid
Almond leaves.
Alder cones.
Rooibos tea.
Kent Black Water Expert which has not been available since early Covid times.

I have a pair of hand held TDS meters and a permanet digital monitor on the tank and also used for mixing the changing water to the proper parameters. The tank is only 55 gallons. I had wanted the fish in this tank for almost 10 years before i was willing to try what was required. I lost a fair number of them early on learning what not to do., but most who try do this as well. But these fish are way more difficult to keep than most, The work needed is similar but the amount of wiggle room varies.

Changing water params and keeping them fairly stable is not as easy as it may sound. This site below may help a bit. It keeps it simple which means not as in depth as one can get. It also makes it easy to understand. I started there a long time ago- before social media.
Beginner FAQ: Water Chemistry

 

[seangee]

With a KH of 6 (assuming dKH) you have a sufficient buffer. If you change 50% of your water every week your pH will settle at a stable value, whatever that is. My tanks all have different pH values using the same water - there are a lot of factors including bio load and plant density. Don't sweat about it. Your current readings suggest there is still some RO in the tank. I'd suggest 50/50 RO / tap water, but that's your choice.

 

[GaryE]

There is some advice above I think is very wrong and should not be followed. Please, don't add crushed shells in your situation. I can only assume the poster didn't read the start of your thread to have suggested that.

@seangee has excellent advice to follow, based on what you asked.

If you have nitrite problems, change some water. It won't be a lot of work and it'll do the job. Adding salt as suggested a couple of posts up is an old, very short term trick.

 

[TwoTankAmin]

Well please note that the OP state two thinhs about his parameters which I guess nobody noticed. the first was

"My pH was originally between 7.5 and 8, the GH was 180 (at least), and the KH was between 120 and 180."

So if the assumption is the OP is reporting in dgs, can anything swim in that? On the other hand if it is PPM then it would translate to between about and 10 DG using 17.8ppm = 1dg. So I assumed the most reasonable thing, the numbers were ppm. Of course the pH was higher then.

The OP also reported having added RO water and then the following reading:
"
pH 6.4 (or less - this is the lowest reading available and I'm worried it's even lower)
KH 6
GH >14
Nitrites less than 1 (I'm at the end of cycling - they'll soon be 0)
Nitrates between 10 and 25"

So what was the 6? If it was ppm then there is clearly a serious issue. If it was dg it would still account for some of the drop. Or was the OP using two different scales without mentioning this?

Then the final change wast reported- "I phased out the RO water - which I'd only just started introducing anyway - 2 weeks ago."

So, ignore whomever you want. But the only way to drop the pH in a tank from between 7.5 and 8 down to 6.4 or less is to overcome KH. That can be done in two ways easily and I use both. I mix my tap with RO/DI water and I often add muriatic acid. I also use alder cones and almond leaves to help keep parameters stable and the water on the soft side as well as for staining.

Altering one's water parameters is chemistry. It works the way it works in spite of what we might think. The one thing that is for sure is it it is much easier to raise the paramters and hold them at higher numbers than one's source water is than it is to do the reverse.

edited for typos and spelling

 

[seangee]

So if the assumption is the OP is reporting in dgs, can anything swim in that? On the other hand if it is PPM then it would translate to between about and 10 DG using 17.8ppm = 1dg. So I assumed the most reasonable thing, the numbers were ppm. Of course the pH was higher then.

The OP also stated that they changed test kits and the new one used a different scale. So my assumption is ppm initially and degrees subsequently

 

[On_a_dishy]

Thanks, all. Nitrites fell to 0 yesterday so I’m happy about that! I’ll stop worrying about the pH, and I’m thinking of re-scaping to get rid of the soil and plants as not much success is going on there. Might move to sand with a few pebbles.

 

[TwoTankAmin]

Adding salt for nitrite is not a trick And it is the chloride in salt that you want. The science states that when performing research into the effects of nitrite they are worthless unless on includes the data for chloride. Gary is lucky to keep fish in a tank rather than on a fish farm say in a 50,000 gallon pond. It is a bit difficult to do a few 25,00 gallon water changes to deal with nitrite, But what do the people in aquacuture know, They have onlybeen dealing with nitrite for decades using chloride. They should have just asked somebody above why this was a trick and then asked for the better faster way.

pH is unimportant, to me. It is an indicator of water hardness, which is crucial.

pH is not an indicator of water hardness. Here are some examples:

"Water hardness follows the following guidelines. The unit dH means ``degree hardness'', while ppm means ``parts per million'', which is roughly equivalent to mg/L in water. 1 unit dH equals 17.8 ppm CaCO3. Most test kits give the hardness in units of CaCO3; this means the hardness is equivalent to that much CaCO3 in water but does not mean it actually came from CaCO3.

General Hardness

0 - 4 dH, 0 - 70 ppm : very soft
4 - 8 dH, 70 - 140 ppm : soft
8 - 12 dH, 140 - 210 ppm : medium hard
12 - 18 dH, 210 - 320 ppm : fairly hard
18 - 30 dH, 320 - 530 ppm : hard
higher : liquid rock (Lake Malawi and Los Angeles, CA)"

The water parameters in the shallows of Lake Towuti are as follows: High pH and soft water.

Temperature (°C)	29.2
pH	8.4
General hardness (°GH)	6
Carbonate hardness (°KH)	4
Conductance (μS)	146
Total dissolved solids (ppm)	73
Oxygen (mg/l)	7.15

Or how about
The water parameters in the shallows of Lake Matano are as follows: still soft water and higher pH

Temperature (°C)	28.7
pH	8.5
General hardness (°GH)	7
Carbonate hardness (°KH)	5
Conductance (μS)	175
Total dissolved solids (ppm)	87.5
Oxygen (mg/l)	6.93

As for the reverse, lower pH but harder water. I see this myself. In order to get my pH lower I will add muriatic acid to the water. When I do this my tds go up, not down.

pH is mostly entwined with KH which is often referred to as temporary hardness. A lot of the confusion can be caused by the fact that hardness is not equal to conductivity/TDS. The latter includes more things in the water than does hardness. To make it simple to understand. get some pure water (distilled or RO/DI). Divide it into two containers. check the hardness and TDS of the first container which serves as the control. Then add some salt to the second container and test for both hardness and TDS. See what results you get.

Total dissolved solids (TDS) refers to a measure of all inorganic solids dissolved in the water. This means that it will measure ions that contribute to water hardness, tike calcium, but also those that do not, like sodium. The TDS measurement is a better reflection of the total mineral content of the water rather than a water hardness measurement. However, for estimation purposes, the water hardness can be roughly calculated by dividing the ppm (parts per million) measurement of the TDS by 10 giving a hardness value with an error of only 2-3 French degrees. TDS measurements can also be derived from relative conductivity measurement

Conductivity is similar to TDS measurements. Conductivity is a measure of the ability of a substance to conduct electric current. Conductivity measurements offer a rapid and non-destructive way to measure ion content in the sample. The conductivity measurement is made with an electronic sensor or meter in micro/milli-Siemens per centimeter or ppm. Conductivity increases with increasing ion content, which means that in most cases it gives a good approximation of the TDS measurement using the conversion factor of 1 ppm = 2 uS/cm. Conductivity is temperature sensitive and is typically standardized to 25°C. While conductivity is a convenient way to get an approximation of the hardness of water it does have the drawback of combining all ions in the measurement, including those that do not contribute to the water's hardness. This hardness approximation gives an error similar to the TDS measurement of 2-3 French degrees of hardness.
Can you measure water hardness with a conductivity sensor or TDS sensor? Yes, however it depends on the accuracy that you want to have in your measurement.