Fertilizer

[dR3ws3r]

Quick question, does anyone know if aquarium plant fertilizers (I'm using Seachem micro and macros) affect the PH of the tank?

 

[Rocky998]

That is a good question I have never thought of!

 

[Byron]

They do not affect GH/KH/pH if used properly, by which I mean not overdosed. "Hard" minerals like calcium and magnesium will increase GH and pH but this involves far greater levels than most basic comprehensive fertilizers, such as Seachem's Flourish Comprehensive Supplement (the liquid) or their Flourish Tabs. I used both products for many years, and they had no effect on GH/KH or pH.

Some "fertilizers" can, such as Seachem's Equilibrium. I was using this for a few years in two large tanks, and at a level that increased the GH from zero (or so close to zero it could not be measured) to 5 dH [= 90 ppm]. It did not affect pH however.

 

[Rocky998]

What about API leaf zone? The two main ingredients are iron and potassium

 

[Colin_T]

they shouldn't affect the pH

 

[StevenF]

Quick question, does anyone know if aquarium plant fertilizers (I'm using Seachem micro and macros) affect the PH of the tank?

it's a complicated answer but in most cases you won't see anything.

The salts used un fertilizer on their own do not effect PH. because they are neither acidic or alkali.

however that said for micros you want the ingredients dissolved in acidic water. If the water is not acidic the ingredients start to oxidize and become less potent. So just adding the fertilizer will reduce your PH but a few milliliters in a large tank is not going to have a noticeable effect.

But over time as plants consume the fertilizer the PH can change. plant absorb nutrients at different rates. For example a GH booster may be made up of magnesium chloride and Calcium sulfate. Plants need all of these elements. But they need a lot of calcium and magnesium and very little chlorine and sulfur. So the end result is that over time as the plants consume the calcium and magesium Excess chlorine and sulfur will build up in the water. This excesss will make the water increasingly acidic. Over a couple of days you may not notice it. But over a a week or 2 you could see a PH drop and or a KH drop. This is most noticeable in very soft water. in water with a lot of KH it is a lot harder to see. It is basically impossible to make a fertilizer perfectly balanced so you don't get excess of something. So many fertilizers over time can make the water more acidic or even more alkaline but generally KH and other factors contracts this so you often don't see it.

Also it is possible to for an excess to push the PH up. Many fertilizers use potasssium nitrate.as a source of potassium and nitrogen. Plant need a lot of nitrogen but only about 60% of potassium so you get and excess of potassium. Which will push the pH up.

One unusual reaction occurs with Calcium and magnesium carbonate which occurs naturally in hardware. Carbonate is CO3 95% of the dry mass in plants is carbon with calcium and magnesium making up less than about 2%. So plants consume the carbonate and leaving behind the calcium and magnesium causing pH to go up. But when the lights turn back off the excess calcium and magneisum reacts with CO2 from the air and reverts back to carbonates. End result is in some tanks you will see the PH at 7 in the morning when lights turn on. But just before lights turn off the PH will be above 7. Then the next morning the PH willl be 7 again. The first time I saw this I was trying out a new brighter light. IN the morning PH owas 7 but just before lights went off it was close to 9. Next morning it was back at 7. The only solution to this problem was to dim the light.

IN any aquarium with living animals or plants the water chemistry and PH is constantly changing.

 

[TwoTankAmin]

Not all plants use carbonates or bicarbonates, but the nitrifying bacteria do. Both can also use CO2. They are also mostly what contribute to KH in an aquarium. And as we all should know, the higher the KH in a tank the more difficult is is to lower the pH. Calcium, on the other hand contributes to GH. If we add calcium carbonate to a tank we will raise both KH and GH.

Sodium bicarbonate in a tank does two things, it adds sodium and it adds bicarbonates and that part will drive the pH towards an equilibrium value of 8.2 pH. Unfortunately, a lot of fish will not do well with the elevated sodium.

However, plants which live completely submerged will pretty much all chose co2 over carbonates when both are in adequate supply.
“In this study, we’re able to show that yes, when in an environment where carbon dioxide is limited, then plants use strategies to extract carbon from bicarbonate,” said Lars Iversen, principal investigator for the study and a research fellow at the School of Life Sciences.............

The study, which focused specifically on aquatic plants that live completely submerged, also showed that when plants have easier access to carbon dioxide, they will use that as their carbon source, even if bicarbonate is available.

from https://news.asu.edu/20191114-asu-study-shows-some-aquatic-plants-depend-landscape-photosynthesis

It is normal, as posted, for the pH to change from night to day. It is also true for other things in water. CO2 in water creates carbonic acid which in turn will lower pH. Plants use CO2, fish exhale CO2 and surface agitation allows for CO2 to enter or leave the water. So it is easy to see why parameters are contantly changing within a range when things are working normally. Who is using what in a planted tanks can change as the plants grow or when they get pruned back a bunch. They can change when one changes co2 levels or fertilizer levels.

As far as I know the best way to avoid the lack or excess of things in a tanks is via water changes. They remove the excesses and will add back some things. What they do not add back, we add instead. Depending on the types and mass of plants in a tank, how often fertilizing is needed as well as how often to do water changes can change.

Correct me if I am wrong, but isn't it magnesium oxide which can raise pH rather than magnesium? Also, how much magnesium is required to raise pH? When I needed to hold up the pH in my pressurized CO2 added planted tank, I used a bag of crushed coral (calcum carbonate. But I always used Tropica's comprehensive fertilizers in the tank starting with Mastergrow.

 

[itiwhetu]

Not all plants use carbonates or bicarbonates, but the nitrifying bacteria do. Both can also use CO2. They are also mostly what contribute to KH in an aquarium. And as we all should know, the higher the KH in a tank the more difficult is is to lower the pH. Calcium, on the other hand contributes to GH. If we add calcium carbonate to a tank we will raise both KH and GH.

Sodium bicarbonate in a tank does two things, it adds sodium and it adds bicarbonates and that part will drive the pH towards an equilibrium value of 8.2 pH. Unfortunately, a lot of fish will not do well with the elevated sodium.


from https://news.asu.edu/20191114-asu-study-shows-some-aquatic-plants-depend-landscape-photosynthesis

It is normal, as posted, for the pH to change from night to day. It is also true for other things in water. CO2 in water creates carbonic acid which in turn will lower pH. Plants use CO2, fish exhale CO2 and surface agitation allows for CO2 to enter or leave the water. So it is easy to see why parameters are contantly changing within a range when things are working normally. Who is using what in a planted tanks can change as the plants grow or when they get pruned back a bunch. They can change when one changes co2 levels or fertilizer levels.

As far as I know the best way to avoid the lack or excess of things in a tanks is via water changes. They remove the excesses and will add back some things. What they do not add back, we add instead. Depending on the types and mass of plants in a tank, how often fertilizing is needed as well as how often to do water changes can change.

Correct me if I am wrong, but isn't it magnesium oxide which can raise pH rather than magnesium? Also, how much magnesium is required to raise pH? When I needed to hold up the pH in my pressurized CO2 added planted tank, I used a bag of crushed coral (calcum carbonate. But I always used Tropica's comprehensive fertilizers in the tank starting with Mastergrow.

And this is where a hobby becomes so complicated that everyone, but a scientist jumps ship.

 

[StevenF]

Correct me if I am wrong, but isn't it magnesium oxide which can raise pH rather than magnesium? Also, how much magnesium is required to raise pH?

magnesium and calcium are very similar. iMy understanding is that n their pure metal state they have no effect on PH. However in air they corrode to a oxide. but when the oxide gets wet it covers to hydroxide which does push PH up. And then they converts to carbonate.

carbonates of calcium and magnesium can exist in bicarbonate or carbonate state in water. The bicarbonate state dominates in acidic water and push PH up but not as strongly as the hydroxide from. But once PH exceeds 7 the bicarbonate converts to carbonate which does not push PH up.

So Calcium and magnesium carbonates keep the PH close to 7. In sea water tother nminerals adjust to PH up to 8.

In comparison sodium and potassium bicarbonate is always in the bicarbonate state and will continuously push the PH up. So calcium and magnesium is the best choice to buffer the water. but unfortunately dry carbonate doesn't dissolve iwell in water. So most PH broducucts on the market use sodium and potassium bicarbonate.