Seachem Purigen Head Scratcher

[Hufsa]

I suppose I should take the blame for giving the all clear to a 0 KH. The OP was struggling to get the KH to stay above 0, as the new soil was absorbing it fairly immediately. I wasn't sure if there was any point to making a huge effort to fight the soil on this. But I agree that 0.5 to 1 degree KH would probably help ensure the PH readings are correct, both for monitoring the CO2 injection, and also to clarify what's going on with the Purigen situation.
Hopefully he is able to get the KH to stay stable in the tank.

So should we suggest the OP add a little bit of carbonate salt to their water change water before adding it to the tank?
I think we should bring this discussion back to the practical so the OP knows what to do.
Since this is a planted tank we usually want to avoid adding Sodium (Na), so Potassium Bicarbonate could be a good choice. Ive seen mention of Calcium carbonate but haven't used this myself, is it a feasible option in terms of solubility? 0.013 g/L (25 °C) vs the potassium salt's 22.4 g/100 mL (20 °C)

 

[hypnogogia]

…or potassium carbonate…

 

[dw1305]

Hi all,

Maybe I've poorly understood. But pH always means the amount (activity) of hydrogen ions. Besides, [H+]*[OH-] is constant, which means that if we know [H+], we also know [OH-].

I think this is back to the self ionization of water, there is a thread on Apistogramma forums with the chemistry, I'll see if I can find it.

Cheers Darrel

 

[Happi]

I strongly agree! Zero KH is really an anomaly, best entertained by the expertly skilled plant grower - not even sure if @Happi, @plantnoobdude et al. are doing that.

Cheers,
Michael

actually 0 KH has been quite standard for me for several years now. for those who use acidic soil such as ADA aqua soil, their KH is likely to reach 0 even if they begin with 1-2 dkh or so. if they go longer without water changes, the KH will likely reach that 0 range. Honestly, I see no real benefit for messing with the KH at all, I find the PH to stay within 5 PH range and never seen it swing in sudden manners. many Plant and fish highly benefit from such PH anyway.

I find it more dangerous to mess around with the KH than having it at 0.

 

[hypnogogia]

I strongly agree! Zero KH is really an anomaly, best entertained by the expertly skilled plant grower

I think the key part here is “expertly skilled plant grower” which you, @Happi, undoubtedly are. For someone starting out in the hobby, using RO, I’d suggest it’s best to remineralise and have some KH so as to be able to maintain a stable pH.
i am interested, though, in what way do you see messing with KH as more dangerous than having KH of 0?

 

[dw1305]

Hi all,

But pH always means the amount (activity) of hydrogen ions. Besides, [H+]*[OH-] is constant, which means that if we know [H+], we also know [OH-].

I think this is back to the self ionization of water, there is a thread on Apistogramma forums with the chemistry, I'll see if I can find it.

This thread <"TDS vs hardness">. This is @Regani <"contribution">, he really is a chemist and was my go to source when I <"didn't understand something">.

cheers Darrel

 

[Musicmanryann]

I suppose I should take the blame for giving the all clear to a 0 KH. The OP was struggling to get the KH to stay above 0, as the new soil was absorbing it fairly immediately. I wasn't sure if there was any point to making a huge effort to fight the soil on this. But I agree that 0.5 to 1 degree KH would probably help ensure the PH readings are correct, both for monitoring the CO2 injection, and also to clarify what's going on with the Purigen situation.
Hopefully he is able to get the KH to stay stable in the tank.

So should we suggest the OP add a little bit of carbonate salt to their water change water before adding it to the tank?
I think we should bring this discussion back to the practical so the OP knows what to do.
Since this is a planted tank we usually want to avoid adding Sodium (Na), so Potassium Bicarbonate could be a good choice. Ive seen mention of Calcium carbonate but haven't used this myself, is it a feasible option in terms of solubility? 0.013 g/L (25 °C) vs the potassium salt's 22.4 g/100 mL (20 °C)

Hold up... Firstly there is no blame here, especially not to you, my friend. You have given me nothing but solid advice since day one. Rolling with low KH, for instance, was advice that I had already researched, (for instance) and you gave me the push I needed to be confident in going that direction, rather than worry about it and start dumping baking soda in my tank. I'm not blindly taking the advice of internet strangers and hoping for the best, lol. I have a few brain cells of my own that I rub together on occasion, and I have black belt in Google-Fu. 😅

Even today, with all this conversation about whether or not I should raise my KH, I still think it was the right call. This is because, secondly, this sudden and drastic drop (at least as I perceive it) was no doubt an anomalous event. I have been measuring pH multiple times per day since I started injecting CO2, and while it may be arguable what the pH values mean at < 1 KH, there has been meaning in the pattern of the numbers. That pattern is what changed, and changed a lot, which is what caused me alarm, and brought me here to learn about what may have caused it. I again did that after I did a little research on my own. I'm not one to coming running to internet forums with every little issue when I could've just googled it--those people are annoying, but I digress. 🤣 Compounding my alarm was the poor timing of the anomaly--I had just very very carefully added my first livestock to the tank, setting up what I felt was a great start for them, and they seemed so happy in my tank, and then BAM! Out of nowhere, the first curveball since I started this hobby was thrown my way. Part me feels this is the universe reminding me there is no control, only a wave of organized chaos I need to surf. On the other hand a lot of what excites me about this hobby is that there is a world of things about which to learn. I thought this was a good opportunity to learn about what happened, and maybe make the chaos a little more organized in the process. But again, this was an anomaly. Outside of about an hour or so Wednesday evening, my parameters have been quite stable and within my what I expect and can control given my present level of proficiency.

Further, my low kH level is the natural kH for my tank, I'm not trying to keep it low. Even when I was initially using my tap water with a kH of 3, my aquasoil soaked all of it up so it read <1. Before @Hufsa advised me to not worry about it, I was trying to bump it up with a little baking soda and got nowhere. 🙃 My understanding is this is an engineered function of aquasoil, so I am a little confused why working with low kH isn't more prevalent and understood. I feel at this point, I would start manually adjusting KH if I felt that A) With my aquasoil soaking up KH, I could reasonably adjust it without a worry of significant downstream effects or B) There was an imminent threat to the livestock I have at present levels. Bonus points if there was any consensus here about either of them, which seems may be a challenge. Lol.

But back to the anomaly. As discussed, I opened up the filter last night and removed about a little under a liter of matrix, equal amounts from each tray, which was just enough to fill up the little filtosmart 100 I have for the nano tank I am starting. Win win. I performed the sniff test which yielded no sulfurous smell, only the normal smell of aquarium water. All the matrix still looked quite clean, pretty much the same as when I originally put it in there. No issues there. Still no explanation for the bowl of water with Purigen in it reading pH in low 4's. 🤔 I guess unless people have any more hunches about this stuff, we may just have to shelf the investigation for now until it happens again, which is hopefully never.

I really appreciate everyone's thoughts, guidance and what has turned into a great discussion!

Cheers,
Ryan

 

[MichaelJ]

Here is my Birds Eye understanding of KH as it relates to our planted fish aquariums:

KH measures the amount of CO3/HCO3 in a body of water. We call this alkalinity - the higher the alkalinity the higher the resistance the water will have to pH change.

As CO2 dissolves in water pH goes down. The higher the KH (the more CO3/HCO3 in the water) the smaller(?) and slower this change will be.

Livestock are generally fairly well adaptable to gradual change to pH - we see this all the time in nature and stocked CO2 injected tanks - a ~1 pH change over the course of say an hour or so is generally not an issue. A very rapid swing in pH however is a bad thing for most livestock, but the adaptability to pH change is species depended (range and speed of change - some tetras are extremely well adaptable to very low pH for instance).

While we can (probably) all agree that for plants KH is unimportant as long as it's low! +90% of species can evidently grow fine at elevated KH, some species require low KH - I believe the same species also require low pH in order to maximize uptake, which goes hand in hand with low KH.

When we offer out recommendations on KH we have to take into account that most beginners and newbies won't be able to take all these factors mentioned above into account especially as far as the health-being of the livestock is concerned!

As said, zero KH is expert territory - @Happi and @plantnoobdude knows exactly what they are doing - most of the rest of us needs to be more careful.

just my 2c Saturday rant! 🙂

Cheers,
Michael

 

[MichaelJ]

…or potassium carbonate…

That will do.... For Potassium carbonate (K2CO3) you only need like 2.5 gram per 100 L to raise the KH 1 degree.

I've used Potassium Bicarbonate (KHCO3) for a long time in the past... I am using CaCO3 myself now, but it's a bit tricky to work with and of course adds to GH as well.

Cheers,
Michael

 

[Happi]

As said, zero KH is expert territory - @Happi and @plantnoobdude knows exactly what they are doing - most of the rest of us needs to be more careful.

I believe Most people nowadays are within this territory because most people use RO water, GH Booster and Acidic Soil. only some still add KH, some are still using Sodium based salts to raise the KH, which is quite useless. While some uses more appropriate way to add the KH using KHCO3 and such, targeting 0.5-1 dkh, which too is mainly to add the K rather than KH being the primary focus. in non acidic soil based aquarium, you will almost always will find some presence of KH.

I think the key part here is “expertly skilled plant grower” which you, @Happi, undoubtedly are. For someone starting out in the hobby, using RO, I’d suggest it’s best to remineralise and have some KH so as to be able to maintain a stable pH.
i am interested, though, in what way do you see messing with KH as more dangerous than having KH of 0?

what do you consider stable PH?

tank running with Aqua soil for example with 0 KH, will maintain around 5-6 PH and you will never see it suddenly go from 5 to 7 or 7 to 5, even with the CO2 injection, those changes occur gradually. if someone were to add something to raise the KH using some kind of salt directly into the aquarium, you are suddenly going to push the KH/PH in the 6-7 range, in some cases exceeding the PH of 7, depending on the salt being used to raise the KH. this condition still applies even if the water was prepared in advance for water changes, because the water in the aquarium will likely reach the 0 KH with lower PH if the tank is using acidic soil. under such condition the risk is still there but it is less severe than directly raising the KH inside the aquarium. hobbyist are more likely to kill their fish under such scenarios, majority of them kill the fishes simply by injecting way too much CO2. in another word i must say that: Hobbyist are likely to kill their Livestock with overdose of CO2 than killing their live stock with 0 KH.

keeping the KH close to 0 also lower the chances of Ammonium becoming Ammonia, this is beneficial for those who dose Ammonium based Fertilizer. am not saying 0 KH is must to achieve this goal, but keeping the 0 KH gives you this security.

 

[MichaelJ]

I believe Most people nowadays are within this territory because most people use RO water, GH Booster and Acidic Soil. only some still add KH, some are still using Sodium based salts to raise the KH, which is quite useless. While some uses more appropriate way to add the KH using KHCO3 and such, targeting 0.5-1 dkh, which too is mainly to add the K rather than KH being the primary focus. in non acidic soil based aquarium, you will almost always will find some presence of KH.

what do you consider stable PH?

tank running with Aqua soil for example with 0 KH, will maintain around 5-6 PH and you will never see it suddenly go from 5 to 7 or 7 to 5, even with the CO2 injection, those changes occur gradually. if someone were to add something to raise the KH using some kind of salt directly into the aquarium, you are suddenly going to push the KH/PH in the 6-7 range, in some cases exceeding the PH of 7, depending on the salt being used to raise the KH. this condition still applies even if the water was prepared in advance for water changes, because the water in the aquarium will likely reach the 0 KH with lower PH if the tank is using acidic soil. under such condition the risk is still there but it is less severe than directly raising the KH inside the aquarium. hobbyist are more likely to kill their fish under such scenarios, majority of them kill the fishes simply by injecting way too much CO2. in another word i must say that: Hobbyist are likely to kill their Livestock with overdose of CO2 than killing their live stock with 0 KH.

keeping the KH close to 0 also lower the chances of Ammonium becoming Ammonia, this is beneficial for those who dose Ammonium based Fertilizer. am not saying 0 KH is must to achieve this goal, but keeping the 0 KH gives you this security.

Hi @Happi, I do agree with pretty much everything you said above. However, I think you are speaking from the point of view of a controlled and well understood environment. If the water, as in the OP's case with an immature tank with zero buffer capacity, for one reason or another experiences a sudden release of acid due to a chemical imbalance (as suggested by the rapid drop in pH by shaking the filter) you will get into trouble and pH can swing really fast with potential lethal stress on livestock. I am not arguing that beginners should run their tanks at elevated KH levels if it can be avoided, just that its a good idea to be cautious and err on the safe side by providing a bit of buffer capacity until things are stable (such as soil stops leaching, the tank matures etc.) and more experience is gained. Thats all 🙂

Cheers,
Michael

 

[LightingBamboozled]

I believe Most people nowadays are within this territory because most people use RO water, GH Booster and Acidic Soil.

I think if you surveyed most fishkeepers with plants in the tank you would find they use Tap Water, no additives and pea gravel. Beginners especially will almost always use tap water because they have it on hand and it costs next to nothing.

 

[plantnoobdude]

Just another thing to consider. 0 kH is very good in terms of preventing ammonia poisoning. In fact I used almost fully fresh tropic aquasoil and restarted my tank. Everything was fine and fish did great. pH was at 4-5. If the water was hard, the fish would've succumbed to ammonia levels.

 

[Happi]

I think if you surveyed most fishkeepers with plants in the tank you would find they use Tap Water, no additives and pea gravel. Beginners especially will almost always use tap water because they have it on hand and it costs next to nothing.

in that case they almost never have to worry about increasing the KH, the KH is naturally present in those cases and majority of the unlucky one are stuck with High amount of KH which prevents them from keeping many kinds of plants and fish. here in the USA, majority of people are stuck with the High KH/PH and they are limited to what they could keep, only in some states the the water comes out with low KH/PH.

 

[Hufsa]

Regardless of if one thinks 0 KH is a good idea or not, should we discuss whether adding some KH is a good idea if it disappears shortly after?
Thats where my problem lies really. Lets say @Musicmanryann does weekly water changes*.
If he puts in 1 KH water at the start of the week (at the water change), and the soil strips that down to 0 in, lets say 2 days just as an example.
And the tank runs the rest of the week (5 days) on 0 KH like it "wants to".
Does that make a good and stable system? Wont having the KH yo-yo-ing up and down like that be worse than just letting it be low?
Im not against having "more than 0", but can he actually keep it that way is my question. And if he cant, is it still a good idea to try to raise KH?
(*I think Ryan is currently doing daily water changes because its a brand new tank, but at some point he's going to transition over to weekly or at least something less frequent than daily.)
It has to be practically feasible in order to be a good plan, or?

 

[_Maq_]

No one is talking about adding a lot of alkalinity… @hypnogogia and myself (running my tanks at ~0.5 KH) only suggested having above zero KH - like perhaps 2-3 KH

I think no small part of misunderstanding in this discussion stems from the fact that 1 °dKH is actually quite a big unit, as it corresponds to almost 22 mg/L HCO3-. So, while it is true that natural waters without any bicarbonates can be considered an exception (pH below 4.5 or above 8.3), many waters feature alkalinity well below 1 °dKH in equatorial zone and in tropical zone during rainy season. And in boreal zone such waters prevail absolutely (with minimal relevance to our hobby, though).
Besides, CO2 injection distorts all perception concerning water. If you don't inject CO2, alkalinity above 1 °dKH results inevitably in pH > 7. I have learnt to dose bicarbonates in the range from 0 to cca 15 mg/L to target pH in the range from 5 to 7, and all that is still less than 1 °dKH. Therefore, suggesting 2 to 3 °dKH means either basic water, or necessity to inject quite a lot of CO2.

0 kH is very good in terms of preventing ammonia poisoning.

That's true, but there's a reverse dependence with much more poisonous H2S. The lower pH, the higher share of un-ionized H2S, which is the most dangerous form.
Again, people tend to blame ammonia for all disasters imaginable. I believe it's mostly an unjust verdict. There are many more harmful compounds around, some of them definitely more harmful than ammonia, both for plants and fish.

in what way do you see messing with KH as more dangerous than having KH of 0?

A very common result is a necessity to use iron chelates instead of simple iron salts. Bicarbonates in water column significantly enhance precipitation of transition metals (Fe, Mn, Zn, Cu, Ni).
Besides, some plant enzymes are sensitive to bicarbonates in plats' internal fluids. It has been documented that some plants can take up iron in basic soils if provided in chelated form, yet remain unable to utilize iron when bicarbonate concentration exceeds certain level, species depending.

Ive seen mention of Calcium carbonate but haven't used this myself, is it a feasible option in terms of solubility? 0.013 g/L

Actually I've been using CaCO3 almost exclusively for adjusting alkalinity (and in this way pH). If you use soft powder, you can prepare stock suspension - in contrast to stock solution. Then, before dosing, you have to shake the flask vigorously and suck specified amount with pipette. Pushed into the tank, it resembles smoke or white fog. In amounts I've specified above, it dissolves completely within one to several hours. I've never observed any negative effects concerning plants or fish.

 

[hypnogogia]

A very common result is a necessity to use iron chelates instead of simple iron salts. Bicarbonates in water column significantly enhance precipitation of transition metals (Fe, Mn, Zn, Cu, Ni).
Besides, some plant enzymes are sensitive to bicarbonates in plats' internal fluids. It has been documented that some plants can take up iron in basic soils if provided in chelated form, yet remain unable to utilize iron when bicarbonate concentration exceeds certain level, species depending.

And what if KH is added in the potassium carbonate rather than potassium bicarbonate?

 

[_Maq_]

And what if KH is added in the potassium carbonate rather than potassium bicarbonate?

It makes no difference. I also dose calcium carbonate, but in contact with CO2 it turns into Ca2+ + 2 HCO3-.
Administrators, would it be possible to allow for upper and lower indexes?????

 

[Hufsa]

And what if KH is added in the potassium carbonate rather than potassium bicarbonate?

The reason I suggested potassium bicarbonate is because potassium carbonate is strongly alkaline

 

[Happi]

The reason I suggested potassium bicarbonate is because potassium carbonate is strongly alkaline

I would also recommend using KHCO3