Chemistry question

[Miami Reef]

To raise pH without messing with KH one would need something like sodium hydroxide

Any liquid pH boost additives, including sodium hydroxide, will also increase alkalinity.

 

[Randy Holmes-Farley Verified Community Expert]

, and, Na/Ca Carbonate raises KH less than NaHCO3.

The only way that would happen is if the higher pH (either locally where it is added or in the tank overall) causes precipitation of calcium carbonate. On a per weight added, there is more alkalinity in sodium carbonate than sodium bicarbonate. :)

 

[Lucas Savioli]

The only way that would happen is if the higher pH (either locally where it is added or in the tank overall) causes precipitation of calcium carbonate. On a per weight added, there is more alkalinity in sodium carbonate than sodium bicarbonate. :)

Precipitation can be the forming of a white spectrum when is added to the aquarium water?

 

[Randy Holmes-Farley Verified Community Expert]

Precipitation can be the forming of a white spectrum when is added to the aquarium water?

It is normal for high pH additives to show immediate precipitation of magnesium hydroxide where first added. That material will redissolve.

A slower precipitation of calcium carbonate that does not redissolve will reduce the effectiveness of the alk addition.

This is normal:

What is that Precipitate in My Reef Aquarium? by Randy Holmes-Farley - Reefkeeping.com

Figure 3. The transient cloud of magnesium hydroxide that forms when high pH additives are added. In this case, the alkalinity portion of B-ionic was added to a fairly still portion of one of my reef aquaria.

 

[Lucas Savioli]

It is normal for high pH additives to show immediate precipitation of magnesium hydroxide where first added. That material will redissolve.

A slower precipitation of calcium carbonate that does not redissolve will reduce the effectiveness of the alk addition.

This is normal:

What is that Precipitate in My Reef Aquarium? by Randy Holmes-Farley - Reefkeeping.com

Figure 3. The transient cloud of magnesium hydroxide that forms when high pH additives are added. In this case, the alkalinity portion of B-ionic was added to a fairly still portion of one of my reef aquaria.

So probably that's why I got an impression of the effectiveness threshold of the different alkalinity supplements.
One other thing that was my issue was the low pH (7.8) and normal alkalinity levels (KH 8-10), however that resolved after some weeks.

 

[Randy Holmes-Farley Verified Community Expert]

So probably that's why I got an impression of the effectiveness threshold of the different alkalinity supplements.
One other thing that was my issue was the low pH (7.8) and normal alkalinity levels (KH 8-10), however that resolved after some weeks.

Sorry, I don't understand what you mean by "effectiveness threshold".

 

[Lucas Savioli]

Sorry, I don't understand what you mean by "effectiveness threshold".

I mean: one does more pH raise than KH/ one does more KH raise than pH raise

 

[Randy Holmes-Farley Verified Community Expert]

I mean: one does more pH raise than KH/ one does more KH raise than pH raise

These each have the same total alk effect:

8.4 grams sodium bicarbonate
5.3 grams sodium carbonate
4.0 grams sodium hydroxide

Here's actual experimental data on pH effects for the same total alk added (1.4 dKH):

https://reefs.com/magazine/chemistry-and-the-aquarium-the-relationship-between-alkalinity-and-ph/
I measured to pH change on adding 0.5 meq/L of each of these alkalinity supplements to freshly made salt water (Instant Ocean made to S=35; alkalinity measured to be 2.26 meq/L by titration). Here’s the result for the pH found immediately, and then after 24 and 120 hours of sitting, unstirred, in an open 500- mL beaker:

Supplement	Initial pH	24 hour pH	120 hour pH
none	8.10	8.11	8.21
0.5 meq/L HCO3-	8.06	8.15	8.33
0.5 meq/L CO3–	8.44	8.28	8.34
0.5 meq/L OH-	8.76	8.47	8.33
0.5 meq/L H+	6.91	7.91	8.15

 

[Lucas Savioli]

These each have the same total alk effect:

8.4 grams sodium bicarbonate
5.3 grams sodium carbonate
4.0 grams sodium hydroxide

Here's actual experimental data on pH effects for the same total alk added (1.4 dKH):

https://reefs.com/magazine/chemistry-and-the-aquarium-the-relationship-between-alkalinity-and-ph/
I measured to pH change on adding 0.5 meq/L of each of these alkalinity supplements to freshly made salt water (Instant Ocean made to S=35; alkalinity measured to be 2.26 meq/L by titration). Here’s the result for the pH found immediately, and then after 24 and 120 hours of sitting, unstirred, in an open 500- mL beaker:

Supplement	Initial pH	24 hour pH	120 hour pH
none	8.10	8.11	8.21
0.5 meq/L HCO3-	8.06	8.15	8.33
0.5 meq/L CO3–	8.44	8.28	8.34
0.5 meq/L OH-	8.76	8.47	8.33
0.5 meq/L H+	6.91	7.91	8.15

That's very impressive work!
Thanks for sharing

 

[Randy Holmes-Farley Verified Community Expert]

That's very impressive work!
Thanks for sharing

Thanks and your welcome.

Happy Reefing!

 

[Garf]

Yes, good point!

How have you achieved this? Personally I've utilised the potential energy from a liquid at height and converted this into kinetic energy, a little heat, some sound, and free aeration. In other words, I've cut the line to the sump short and created a lot of splashing. I don't need a silent fish tank anyhow, lol.

 

[rishma]

How have you achieved this? Personally I've utilised the potential energy from a liquid at height and converted this into kinetic energy, a little heat, some sound, and free aeration. In other words, I've cut the line to the sump short and created a lot of splashing. I don't need a silent fish tank anyhow, lol.

Huge air pump, air stones, with air from outdoors

 

[rishma]

How have you achieved this? Personally I've utilised the potential energy from a liquid at height and converted this into kinetic energy, a little heat, some sound, and free aeration. In other words, I've cut the line to the sump short and created a lot of splashing. I don't need a silent fish tank anyhow, lol.

https://www.reef2reef.com/threads/m...-outdoor-aeration-ph-boost-stability.1084802/

 

[Garf]

Huge air pump, air stones, with air from outdoors

Excellent, I've got an air pump and stone, and a tiny skimmer pump going also (little tank)

https://www.reef2reef.com/threads/m...-outdoor-aeration-ph-boost-stability.1084802/

Lol, poked my nose in near the end of that thread, didn't realise it was yours :)

Air is good

 

[Phil Adams]

Thanks folks for your input.
I have weighed everything up and I have decided to stop dosing alk and calc separately, and instead to go with AFF in one doser. That will leave me a doser free should I feel the need to boost the ph with either Kalk or soda ash.
Reason is that on the current alk and calc I am not adding magnesium nor trace elements and I think a balanced additive like AFR will be a forward step rather than a backward step. I will monitor and despair as necessary.
Thanks again for the lively debate, but this is what I’m going to do.
Kindest regards and respect
Phil Adams