High PH, Lower CO2, less plant growth?

[Samuel]

Hi guys,

Is it true that higher PH has less Co2 and if so is adding CO2 a good idea? My ph is 8.4 and I'm growing plants without Co2 with some success but I've heard you'll get better growth with a PH of around neutral. 

True, false, some truth in there?

[face]

Ok from my understanding carbon dioxide doesn’t exist in water carbonic acid does it will turn into bicarbonate then carbonate losing hydrogen to the water as ph increase 

but KH buffering  requires there to be a certain ratio of the 3 and that will give you the ph of your water for the most part 

for example if you put a bunch of carbonate in water the ph will increase but some will turn into the other two until the ratio equalizes plants for the most part can’t use bicarbonate or carbonate but they can use carbonic acid (side note lots of algae can directly use carbonate that why algae grow so well in water without co2) so technically you have less carbonic acid (co2) but it’s a ratio not an amount if you started with 100 carbonic acid by adding more bicarbonate you don’t necessarily have less of the other just a different ratio that is until you hit the saturation limit in which case your see your water boil like carbonated water or Little Rock’s form in your water but you know don’t do the lol 

In short no you don’t really have less co2with lower ph but most plants do prefer low ph because there internal systems have to work less in the lower ph but some have systems to cope with the high ph and so they prefer it

[Tony s]

On 3/6/2024 at 9:50 PM, face said:

but most plants do prefer low ph because there internal systems

Yeah, most plants are as variable as the fish for the most parts. plants actually prefer to have more available carbonate in the water. There is one youtuber who is a big plant grower from Kentucky who raises all his plants in hard water and they do just fine. It really depends on the plant species just like it depends on the fish species.  you can google plant care guides and they will give you a best kept at range. for most beginner plants it usually ranges 6.0 to 7.5 ph. from 1-6 kh. from 2-12 gh. these values are for pogostemon stellatus. jungle val is 6-8 ph, 2-21 kh. and that doesn't include the inherent plasticity in most plants (the ability to adapt).

8.2 is a bit high but not excessively so. you just have to decide what you want and see if it's an option

try this site for help

https://www.learntheaquarium.com/

there are more sites with this info but can't post them via rules (no compete sites that sell )

On 3/6/2024 at 7:49 PM, Samuel said:

higher PH has less Co2

yes, that is true, but higher ph water has more dissolved carbon that is ready to use without conversion. CO2 must eventually be absorbed and converted into a usable form. 

[Mmiller2001]

Ph, has no affect on CO2. Some plants do better in lower pH for other reasons. 

[Tony s]

On 3/6/2024 at 10:52 PM, Mmiller2001 said:

Some plants do better in lower pH for other reasons

Yes. Exactly. There is a wide range of tolerances depending on the plant wanted. As there is in the fish wanted. Research needs to be done by the keeper. But most plants as well as animals carry a decent amount of plasticity and can adapt to less than their ideal situation. Especially if they have already been started in a man made environment. Wild grown plants and animals can be harder to adapt