I have 2 questions about ph

[Asher E.]

1. At what ph does ammonia
turn into ammonium?

2. If there’s a fish that needs ph at 6.5 or higher then can it live in ph of 7.0 that lowers to 6.0 with co2? Or does the ph change from co2 not affect it like that? I know co2 doesn’t affect kh.

 

[Koan]

The pH itself does not affect your livestock.. it's what the pH change means, for alterations in anything else dissolved in your water at the same time, that causes the problems. IE changing relatively safe NH4+ back into toxic NH3.

Here is an extended, and at times hilarious discussion on that very topic, way too long to quote here.

 

[Art]

Ammonia exists in water as either the ammonium ion (NH4+) or the non-ionized ammonia (NH 3). Non-ionized ammonia is toxic to fish, while the ammonium ion is non-toxic, except at extremely high concentrations. At neutral pH 7 and ambient temperature, almost all the ammonia exists as NH4+. As the pH and temperature increase, the amount of NH3 increases and the amount of NH4+ decreases.

This table gives you an idea of how it ranges based on pH:


As you can see above, we typically don't worry about ammonia toxicity in planted aquariums as we are almost always within the very, very low range.

More over, IMHO, fish, like most things, can live just fine within a range of pH. Actually, what we are really talking about is the hardness of the water and what the particular species is typically adapted to in the wild. However, fish are surprisingly adaptable.

In your second question, what is dangerous to fish is not the drop in pH that happens when you add CO2 but rather the amount of CO2 reducing the ability of the fish's blood to transport oxygen. Essentially, the fish suffocates form lack of oxygen.

The above table doesn't factor in temperature that can also impact this topic but, again, at tropical temperatures that our aquariums exist, this is generally not an issue.

 

[Art]

An interesting topic to take from your questions is, why are we then so concerned about having large amounts of biological filtration in our systems? We read so much about ammonia spikes leading to problems in the aquarium. Why?

In a well stocked planted aquarium, the plants are more than happy to take up all the ammonium in the water as that is their preferred nitrogen source.

In reality, are our large canister filters more beneficial because of the flow they create than because of their capacity for nitrification ??

 

[Kwyet]

What can happen though, is if you suddenly add higher pH water to water that is already low, then all the ammonium suddenly becomes ammonia and kills your fish. That’s why so many prefer the plop and drop method for adding mail-order fish to their aquariums, and another reason to be sure to add Prime when doing a water change. I understood the turning point to be around pH 6.4. That’s been my understanding for a long time. Please correct me if that’s not accurate.

 

[Naturescapes_Rocco]

An interesting topic to take from your questions is, why are we then so concerned about having large amounts of biological filtration in our systems? We read so much about ammonia spikes leading to problems in the aquarium. Why?

In a well stocked planted aquarium, the plants are more than happy to take up all the ammonium in the water as that is their preferred nitrogen source.

In reality, are our large canister filters more beneficial because of the flow they create than because of their capacity for nitrification??

I currently run ZERO bio media in my filters in my heavily planted tanks without any issues. I think bio media is helpful during the cycle startup, but can be phased out once plants are established. I think it's a remnant from the "nearly barbaric" days of fish-centric aquarium hobby. YMMV!

 

[Asher E.]

Thanks everyone