A lot of talk about pH and coral growth lately, here is an interesting study...

[PizzaOven]

Hi All,

I've been seeing a lot of discussion about pH in the hobby lately. Unlike many years ago when I started the hobby, there is now a trend to chase pH. Guys like Chris at ACI have been very vocal proponents of pH as a primary driver of coral growth. Clearly, this works for him and his coral farm. Others claim that it doesn't seem to have much impact. I thought it would be interesting to look for peer-reviewed research on the matter. I stumbled across this paper from 2014: Coral calcification under daily oxygen saturation and pH dynamics reveals the important role of oxygen

In this study, the authors measured both the light and dark calcification rates of Acropora Millepora at different pH and oxygen levels (hypoxia, normoxia and hyperoxia). All of the details are laid out in the article: lighting, flow, calcification measurement technique, etc. Here is a summary of the study:

This study is suggesting that along with pH, O2 plays a big role in calcification. at Normoxia, increased pH greatly enhances light calcification rates, but at hyperoxia, this effect is completely negated! I wonder if people who report success with raising pH have normoxia systems, and those who don't are running at hypoxia or hyperoxia. This makes me want to go out and purchase a dissolved O2 meter

Food for thought! I think this issue is a bit more complex than we think. Curious to hear what your thoughts are on this study. Is it representative of what we do in the hobby?

 

[Vincerama2]

Thanks for sharing that study! At some point I think we are just chasing numbers and honestly ... can we control every thing?

What I do know is that when my return pump broke, the lack of oxygen killed off all my beautiful fish, so I'm not going to chase hypoxic conditions, and providing fresh outside air to my skimmer is cheapish.

According to this study, chasing pH with kalkwasser rather than low CO2 bubbles in the skimmer would be a better solution for pH chasing. (no increase in O2, but increase in pH...temporarily probably.)

V

 

[PizzaOven]

Thanks for sharing that study! At some point I think we are just chasing numbers and honestly... can we control every thing?

Yeah for sure. I personally think part of what makes this hobby fun is having stuff to chase and seeing results (good or bad!)

I'm curious to see how my O2 and pH numbers compare to what the authors found for best daytime calcification rate: pH 8.4 and O2 100% (6 mg/L).

I know my pH runs a bit low (8.0-8.2), so likely I could benefit from increasing pH (to 8.4) if my O2 level is close to 6 mg/L. What's particularly promising, if this study maps well to our reef aquariums, is that I could increase my calcification rate by a whopping factor of 3X!

I'm really tempted to purchase this dissolved O2 sensor from Milwaukee (MW600). It's on sale at SaltwaterAquarium.com right now. If I decide to buy it, I'm will be happy to share it with other members.

 

[grizfyrfyter]

Thanks for sharing that study! At some point I think we are just chasing numbers and honestly ... can we control every thing?

What I do know is that when my return pump broke, the lack of oxygen killed off all my beautiful fish, so I'm not going to chase hypoxic conditions, and providing fresh outside air to my skimmer is cheapish.

According to this study, chasing pH with kalkwasser rather than low CO2 bubbles in the skimmer would be a better solution for pH chasing. (no increase in O2, but increase in pH...temporarily probably.)

V

Kalk is amazing for this because it binds to CO2 in the water and removes it.

 

[Vincerama2]

Kalk is amazing for this because it binds to CO2 in the water and removes it.

I use kalk was my top off. I mean, my ATO water pumps into a DIY kalk mixer, then into the tank. However, I've heard of folks simply dosing kalk as a one-part supplement (which it is), but through a doser sort of match evaporation rate so that it is dripped at a known quantity for control purposes. My ATO pushes kalk whenever it feels like it.

Funny thing is that despite all the two parts and one parts (All-For-Reef = Calcium Formate?), kalkwasser is still one of the best ways to keep alk and calc at desired levels.


V

 

[JVU]

Comparing the first black bars on those 2 graphs, it is interesting that there is more calcification in the coral in the dark than in the light, under the same normal O2 and pH levels. I’ve found I have to continue dosing Alkalinity at the same high rate I use in the afternoon until about midnight or so to keep a steady Alkalinity level, which fits with large amount of continuing consumption into the evening.

 

[PizzaOven]

Comparing the first black bars on those 2 graphs, it is interesting that there is more calcification in the coral in the dark than in the light, under the same normal O2 and pH levels. I’ve found I have to continue dosing Alkalinity at the same high rate I use in the afternoon until about midnight or so to keep a steady Alkalinity level, which fits with large amount of continuing consumption into the evening.

I was surprised to learn dark calcification is even a thing. I assumed that calcification was directly tied to photosynthesis happening in the zooxanthellae.

 

[JVU]

I was surprised to learn dark calcification is even a thing. I assumed that calcification was directly tied to photosynthesis happening in the zooxanthellae.

Photosynthesis makes glucose and O2 (not energy directly), which are then converted into energy for metabolism and growth. But in the process, the glucose acts as energy storage to continue to fuel metabolism after the sun goes down. Similar to how we still have blood glucose for metabolism even if we haven’t eaten in a few hours.

But yeah, I was surprised at the magnitude of ongoing calcification after the lights turn off. It doesn’t slow down for several hours.

 

[grizfyrfyter]

I use kalk was my top off. I mean, my ATO water pumps into a DIY kalk mixer, then into the tank. However, I've heard of folks simply dosing kalk as a one-part supplement (which it is), but through a doser sort of match evaporation rate so that it is dripped at a known quantity for control purposes. My ATO pushes kalk whenever it feels like it.

Funny thing is that despite all the two parts and one parts (All-For-Reef = Calcium Formate?), kalkwasser is still one of the best ways to keep alk and calc at desired levels.


V

I did that for the first two years.

I eventually switched to dosing it with a pump. It's difficult because it isn't as concentrated as a 2 part would be, you have to dose more and I found that when my tank was really rocking, the alk consumption was higher than the evaporation rate sometimes. Calcium reactor + kalkwasser is the best method I've ever tried.

 

[Arvin R]

I'm currently dosing kalk with a Kamoer X1 pump every 2 hours. Full satutation at 2tbls/gal 250ml when lights are off at 500ml when lights are on and everytime I test my alk is 7.9/8.0 stable. My kalk res is a 5gal ato container so I have to mix up kalk every 5 days or so. I did add a CO2 scrubber to the skimmer intake too and pH is 8.3 through the day. I'm going to disconnect the CO2 scrubber for a day over the weekend as I don't think it's making a difference at all as I recall seeing 8.3 already with just kalk dosing. I also grabbed a jebao wifi doser and will switch to dosing every hour (not sure if that will make a difference in anything or not). I also need to setup my KH Gaurdian too this weekend.

 

[Vincerama2]

I did that for the first two years.

I eventually switched to dosing it with a pump. It's difficult because it isn't as concentrated as a 2 part would be, you have to dose more and I found that when my tank was really rocking, the alk consumption was higher than the evaporation rate sometimes. Calcium reactor + kalkwasser is the best method I've ever tried.

Before the dark days of Wifebane, I had a nice 58g tank and ran a CA Rx and my DIY Kalk mixer for ato. Things grew like crazy in it. I had coralline algae growing out in shelves off the walls and an SPS so large that I donated it to Steinhart's because it was too big for the tank! I gave away tons of pavona and montipora at frag trades. Then ... Wifebane. 180g of no coral growth.

In fact it has zero coralline in it. Before a pump failed and killed all my fish, I sent the water away to a lab for testing and the noted something like 200 ppm nitrates! My kids loved feeding the fish and the fish loved eating and pooping. But they are gone now and for the first time in a long time, coral are actually growing in my tank. Unfortunately that includes the 10 million majano in the tank., I'm thinking of a tank reboot, or at least a total rock swap.

V

 

[grizfyrfyter]

I chased high nutrient in the 170 for months before I noticed cat food in the sump and auto top off tank.

I now know it's my daughters cat. If I leave the stand open, she will carry food over and drop it in the water.

 

[BAYMAC]

I chased high nutrient in the 170 for months before I noticed cat food in the sump and auto top off tank.

I now know it's my daughters cat. If I leave the stand open, she will carry food over and drop it in the water.

awe man, funny, not funny.