dKH and substrates which buffer pH?

[wolfiewill]

One concern I am having with changing to the organic, pH buffering substrates is the effect on dKH. The reality of living with city of Ottawa water is that it must be buffered up - from a tap dKH of 2.5-3, to 4 degrees (plus) for good plant growth (generally). When aqua soil, Netlea or Fluval are the primary substrate, will it be possible to maintain a minimum of 4 dKH? Or will I struggle to get it up and keep it up? I also add CO₂ to lower the pH and provide carbon for efficient plant growth: Is the buffering effectively both ways or will I have to reduce CO₂ rates to ensure the pH stays within a reasonable range? Does anyone have experience moving from Seachem's fluorite to any of these substrates who can enlighten me on this concern?

[charlie]

I`m not sure where you are getting the info about 4 DKh + is a requirement for good plant growth, but i`m sure it`s out there on the world wide web or some book, that maybe so but can tell you from personal experience in using the Fluval Stratum in my 20 gallon long for testing i got good growth & then some since i started it in Feb. i think, i have never tested the DKH & i`m in the city & injecting CO2.
The Fluval shrimp & Plant stratum is still buffering true to form as advertised despite reading on several forums how it depletes & stop buffering after 3 months, sucks to have their water  .
Regards

[fischkopp]

Maybe your question should be: do I need to harden the water with these substrates when used in soft water, or do they supply an sufficient amount of calcium/magnesium to the plants?

I don't have the answer to that question as I haven't yet used these new soil/ceramic based substrates. But I can understand where you are coming from. Ottawa city water doesn't supply enough Calcium for healthy plant growth in my tanks, so that it has to be supplemented in form of Ca(NO3)2 or CaSO4.

[wolfiewill]

Maybe your question should be: do I need to harden the water with these substrates when used in soft water, or do they supply an sufficient amount of calcium/magnesium to the plants?

I don't have the answer to that question as I haven't yet used these new soil/ceramic based substrates. But I can understand where you are coming from. Ottawa city water doesn't supply enough Calcium for healthy plant growth in my tanks, so that it has to be supplemented in form of Ca(NO3)2 or CaSO4.

You may be right: Does one really need to worry about KH as it's only indicative of Ca/Mg availability to plants in the water column? If the substrate provides adequate amounts, the amounts in the water column may be irrelevant.

But what about buffering pH from going too low? Can it be a problem?

[exv152]

You may be right: Does one really need to worry about KH as it's only indicative of Ca/Mg availability to plants in the water column? If the substrate provides adequate amounts, the amounts in the water column may be irrelevant.

But what about buffering pH from going too low? Can it be a problem?

To answer your question about whether to worry about KH, my answer is yes. KH is your tank's pH buffer and if it goes to 0º then you could have a pH crash in your tank that kills everything, including beneficial bacteria. I had it happen with flourite substrate, but it was because I was doing a high tech set-up with lots of CO2 injection and didn't pay attention to a KH test result reading 0, when the next day the pH crashed. As long as it reads somewhere above 2 degrees you should be ok, regardless of the substrate you use. Also, turn off the CO2 at night. Something else I learned early on.

[wolfiewill]

To answer your question about whether to worry about KH, my answer is yes. KH is your tank's pH buffer and if it goes to 0º then you could have a pH crash in your tank that kills everything, including beneficial bacteria. I had it happen with flourite substrate, but it was because I was doing a high tech set-up with lots of CO2 injection and didn't pay attention to a KH test result reading 0, when the next day the pH crashed. As long as it reads somewhere above 2 degrees you should be ok, regardless of the substrate you use. Also, turn off the CO2 at night. Something else I learned early on.

That's what I've been led to believe from the literature. And although I've not had a complete crash, I do believe I've been close several times when I was just beginning. The pH dropped like a stone over a couple of days after a small water change. In each case, it was in low tech tanks. I now use CO2 in half my tanks: on 1 hour before lights on - off 1 hour before lights off; and do 50% water changes in low tech tanks weekly. And in each high tech tank I have been buffering up to 4ish for years now. I'm on my way to Toronto Saturday and would like to purchase a bag of aqua soil to try in a low tech tank (first). I am worried about the pH dropping too low since the ADA product removes carbonate hardness, and so adding KH boosting chemicals is probably not going to work as a buffer.

I'll ask the people in Aqua Inspirations. Perhaps they'll know.

[exv152]

BTW, this may be too late, but I was just in scarborough and AI is out of aquasoil.

[wolfiewill]

I have spoken to Sam at Aqua Inspiration: He said our water sounds like the tap water in Vancouver with which he has experience. He said the the pH would level out at about 5.0 with aqua soil!!!! He said we would need to buffer to keep the KH up (?). Which doesn't make sense if one of the benefits of the aqua soil is to remove carbonate hardness. It sounds to me that it would only shorten the life of the buffering capacity of the substrate, making it inappropriate for places with low pH/KH tap water. However, it may have been a misunderstanding on my part but this is what I took away from our conversation. He also said that another substrate may be more suitable for our situation.

As a result, I bought some Fluval substrate and laid it on top of 1" of fluorite red. I have about 1 to 1.25 inches of Fluval in a 10 gallon, low tech tank. After a week, I tested the KH and GH and found that these results are now reversed: typically, my tap water has a KH of about 2.5 (plus or minus 0.5 degrees), and the GH is about the same indicating that the GH is made up of mostly carbonate hardness (non-carbonate hardness + carbonate hardness = total or general hardness). The water hardness after a week was reversed: a KH test gave no reading (less than 1 degrees KH), and the GH was 3.0 degrees. I did ask Sam if the aqua soil acted as a cation exchange medium and he said yes. But he answered too quickly, and with the language issue, I wasn't sure if we were really talking about the same thing. But now with this result (and, yes it's only one result) I am starting to wonder if that is in fact what is happening. The cations of the original carbonate molecules are exchanged for noncarbonate cations?

I'm running on here. So can anyone make sense of what I'm saying? Do I make sense to any of the chemists out there?

[charlie]

The chemistry in this is way above me, but i`m of the understanding that most soil based substrates are high CEC/cation, including Aquasoil, never did find any #`s .
On another note i did some testing today of my tap water & it confirms with your results -KH 2-2.5 DKH & Gh 3DKH
In my Newly set up 79 gallon with all new Fluval plant stratum the reading is as follows -KH- 3DKH & Gh of 5 DKH, i did add 1 Tablespoon of seachem Equilibrium on Fri when i did a WC but i doubt that dose should have raised the GH by 2 DKH

In the just set up 25 gallon with Fluval Plant Stratum that was in use since Feb 2011, i got a KH of 2-2.5 DKH & a GH of 4DKH
In the 15 gallon shrimp tank with 8 month old Fluval Shrimp Stratum the reading was Gh -4DKh & Gh -0 DKH , not sure if it`s the substrate is doing something with the KG or the mosses & anubias & java ferns ( a fair bit) stripping carbon from the KH.
Just thought i`ll share that with you, in the event it helps with your study of these substrates.
Regards

[wolfiewill]

I finally got a reply from ADA on how to expect aqua soil to perform with Ottawa water. Here is the question and subsequent answer from Frank Wazeter at aquariumdesigngroup.com. First the question:

"Frank, one concern I have with changing to the organic, pH buffering substrates is the effect on carbonate hardness. The reality of living with city of Ottawa water (Ontario, Canada) is that it must be buffered up - from a tap dKH of 2.5-3, to 4 degrees (plus) for good plant growth. When Aqua Soil is the primary substrate, will it be possible to maintain a minimum of 4 dKH? Or will I struggle to get it up and keep it up? It is also my understanding that the life span of the buffering capacity of Aqua Soil is proportional to the hardness of the tank water, and that in our case the longevity of AS is expected to be quite good. Also, I add CO2 to lower the pH and provide carbon for efficient plant growth. Is the buffering effectively both ways or will I have to reduce CO2 rates to ensure the pH stays within a reasonable range?
I also want to start a small trial with Aqua Soil in a spare 40 gallon tank (high light, CO2, EI fertilization). My initial tap water pH/KH/GH readings are always in the 7.6 plus, 2.5 and 3.0 ranges respectively. What pH/KH/GH readings should I expect with AS? Does Aqua Soil act as a cation exchange medium, and essentially replace the carbonate cations with something else?
Help me out here, please. Retail sales people are either confused by the question, or if they have an answer, are confusing. At present my only contact with an ADA supplier is a sales rep at Aqua Inspirations in Toronto (a 4.5 hour drive), and he there told me to expect very low pH readings (5.0!!!!) and that I'd have to buffer to maintain pH and carbonate hardness!?!?
Also, I am hearing in various blogs that Amazonia and Africana are noticeably different in their respective effects on the aquarium pH, KH, and GH. Is this true and for a West African biotope tank what should I be using? Regards."

And the answer:

"You are correct about the longevity concerns of AS in your water conditions, and that you have soft water, to buffer the water up you would indeed need a buffer - either Penac W or Seachem Equilibrium. However, that being said, we typically maintain our planted aquariums at 2 dKH in the gallery with RODI water, which allows for more efficient co2 absorption in the water at the 2 dKH level, allowing for less co2 for higher absorption as you can see represented in a chart here:

http://www.aquariumslife.com/aquascaping/fertilizers-and-co2/aquarium_co2_test/

pH concerns in relation to co2 aren't a huge concern: I would focus more on the kH side of things, as over manipulation of the pH through co2 will be difficult, and is often not worth the effort since as long as you are at at least 6.0 pH your aquarium will be fine.

With Aquasoil you should expect:

With a Control Tap Water of 7.6 pH, KH: 2
NH4 is less than 0.1
NO2 is zero
PO4 is 0.5

With Amazonia added to that tap water:
6.8 pH, KH: Less than 1
NH4: 1.0
NO2: .02
PO4: Less than .01

With Malaya:
pH: 5.5, KH: Less than 1
NH4 Less than 0.01
NO2: 0
PO4: less than .01

With Africana:
pH 5.9, KH: Less than 1
NH4: less than .01
NO2: .02
PO4: less than .01

Malaya is for an aquarium with plants that are nurtured over time without frequent replanting because of the softness of it's soil, these are typically very slow growing plants.

Africana holds it's shape better than Malaya, but has less organic nutrients so it again is for more slower growing plants. Amazonia is characteristic by high nutrients and the ability to rapidly grow plants. Malaya is great for shrimp tanks, and Africana and Malaya are well suited for cyptocoryne aquariums.

The best way to think of Aqua Soil is basically as an organic clay, and that to make water soft, organics decompose over time (e.g. Amazon, where decaying plant matter softens the water extremely), and to make water hard we have mineral contents (e.g. Texas where all water is filtered through limestone in the water table).

Aqua Soil as an organic compound releases acidity into the water column and thus saps out the water hardness. What essentially happens is that you have the mineral content and the acid content battling for control of the pH with each one pulling the water to their side, and the stronger element wins this match of tug of war.

What Penac W under the substrate does is help to neutralize some of this acidity effect through supplementation of minerals that increase water hardness and buffer the soil at it's base level.

Frank Wazeter
"

[exv152]

I second what the guy from ADG is saying when he says to worry about KH the most.  As long as you have some buffering capacity, at least 2-4ºkh then you should be fine no matter what the GH or pH are. KH is the most important of the three in a planted tank. I personally use seachem alkaline buffer (for KH), and seachem equilibrium (for GH) from time to time, but the alkaline buffer is really all you need for maintaining a safe KH.

[wolfiewill]

I second what the guy from ADG is saying when he says to worry about KH the most.  As long as you have some buffering capacity, at least 2-4ºkh then you should be fine no matter what the GH or pH are. KH is the most important of the three in a planted tank. I personally use seachem alkaline buffer (for KH), and seachem equilibrium (for GH) from time to time, but the alkaline buffer is really all you need for maintaining a safe KH.

That is my practice exactly. Seachem KH boost with a minimum of 3.5 for all my CO2 fed tanks. So I think this will work with Aqua Soil as well. They target a KH of only 2, but I've had crashes from that range in a matter of a couple of days (in my early years). I'm going to keep my targets to start.

But I'm also going to ask him further questions about using Fluorite (1") under AS instead of buffering with Penac W or Equilibrium. I've tried that in a low tech tank with Fluval Substrate and the KH went to zero (from 2.5) and the GH stayed at 3. The pH bottoms out at 6.8 after a few days without adding any buffers. 

[exv152]

That is my practice exactly. Seachem KH boost with a minimum of 3.5 for all my CO2 fed tanks. So I think this will work with Aqua Soil as well. They target a KH of only 2, but I've had crashes from that range in a matter of a couple of days (in my early years). I'm going to keep my targets to start...

Low tech setups are just as susceptible to KH depletion, maybe even more so, because they use up what ever carbonate hardness is available as a source of carbon. I use the new amazonia aquasoil and so far so good.  I found a safe target range is 4ºdkh, which usually gives you enough room to detect problems ahead of time. If you look at using a med or med/high light source, instead of very high, you may find it easier to control the KH since lighting intensity is the gas-pedal for planted tanks. Med lighting and buffer KH of 4 is probably a safe target no matter what soil you choose. Personally AS is the best choice on the market given it's rich in all the stuff plants need, and it's shown to last the longest.

[wolfiewill]

Low tech setups are just as susceptible to KH depletion, maybe even more so, because they use up what ever carbonate hardness is available as a source of carbon. I use the new amazonia aquasoil and so far so good.  I found a safe target range is 4ºdkh, which usually gives you enough room to detect problems ahead of time. If you look at using a med or med/high light source, instead of very high, you may find it easier to control the KH since lighting intensity is the gas-pedal for planted tanks. Med lighting and buffer KH of 4 is probably a safe target no matter what soil you choose. Personally AS is the best choice on the market given it's rich in all the stuff plants need, and it's shown to last the longest.

OK! That raises some questions that I have:

How stable is the KH with Amazonia? Does it constantly need to be adjusted? Or do you dose only after water changes?

Do you use Penac W? Or anything else in the substrate?

Do you add any liquid iron? And what other fertilizers do you use?

Do you have any problems with plants floating out of the substrate as some people have reported?

Please forgive all the questions but I'm trying to keep the costs down. As a hobby, with 9 tanks already and more to come I suppose, it's expensive. And AS is expensive compared to the alternatives.

[exv152]

OK! That raises some questions that I have:

How stable is the KH with Amazonia? Does it constantly need to be adjusted? Or do you dose only after water changes?

Do you use Penac W? Or anything else in the substrate?

Do you add any liquid iron? And what other fertilizers do you use?

Do you have any problems with plants floating out of the substrate as some people have reported?

Please forgive all the questions but I'm trying to keep the costs down. As a hobby, with 9 tanks already and more to come I suppose, it's expensive. And AS is expensive compared to the alternatives.

AS is more expensive, slightly more @ $40/bag, but well worth the quality. I honestly believe most of the ADA products are over priced with the exception of two of them - the tanks and aquasoil. Outside of that you can get the same look with other knockoff products.  As for other ferts, I use seachem flourish, along with seachem alkaline buffer and equilibrium, together with dry ferts - potassium nitrate & mono potassium phosphate three times a week each. Since I've just begun using the AS it's hard to say, but I'll let you know. But like I said, nothing compares to AS in terms of quality and nutrient content, and I've used good quality plant substrates in the past like flourite and eco-complete.