Impact of changing alkalinity?

spidercrab · Jan 22, 2020

Does alkalinity actually have any effect on our coral? It seems every article or comment I read is about testing alkalinity and extremely tight control. However, I have yet to notice any effect of alkalinity changes on corals over the last 15 years of keeping them. My alkalinity frequently goes from 11 to 7 almost every week and I have never had faster growing coral. Is there really any evidence that alkalinity changes even effect coral at all?

I have 5 tanks and I keep them all as totally separate systems. They range in alkalinity from 7-11dkh any given day. I switch coral between the tanks frequently for pictures, organizing or better lighting and they are open within seconds. The other parameters are pretty well matched such as nitrate/phos, calcium, pH, temperature and salinity.

I also have a nano tank that I drain completely once ever 2 weeks and refill with freshly made saltwater matching just the temperature and salinity. This tank has several SPS species, zoas and LPS. It has grown so full over the last 5 years that I can no longer put my hand in it. At the time of changing it today the alkalinity was actually tested at 5.5dkh! I drained all of the water and refilled it with a fresh 5 gallons of saltwater at 11 dkh and within 1 minute everything is completely open as if nothing happened. That is a change of 5.5 dkh instantaneously with no effect at all and proven for over 5 years.

I am just curious if anyone else has similar experience or doubts about alkalinity monitoring.

pdxmonkeyboy · Jan 22, 2020

I for one would love to see a picture of a beautiful SPS tank that has a 4 dkh swing per week...

Terri Caton · Jan 22, 2020

This is very interesting. Have you noticed any changes in inverts? Do you keep Softies, LPS or anemones?

krash7172 · Jan 22, 2020

I've been surprised that ppl are keeping what I consider to be low alk tanks. Where should we be? SPS, LPS, Softies?

Edit: I'm 10-11 dkh softies and LPS

Dana Riddle · Jan 22, 2020

When I was at Aquatic Wildlife back in the 90's, we installed a large (5 feet tall) Knop calcium reactor on a 1,500 system. It took a large pump to run this thing and we saw a dramatic alk increase overnight. This system housed mostly Acropora specimens. We did see an A. millepora color up (according to some observers) or bleach (according to others.) We presented this info at the Northwest Marine Conference in Seattle in 'the late 90's. Sorry that I can't provide more details - don't have the log books but do have a poor memory.

krash7172 · Jan 22, 2020

I finally have reached the point to even to be part of a conversation like this. Thanks to all.

ReillyReef · Jan 22, 2020

Lets see the proof. Pics of your tanks with that much alk swing.

ReefRondo · Jan 22, 2020

Very interesting. I wonder sometimes how much us chasing numbers and then altering things to rectify off readings makes things worse.

Scrubber_steve · Jan 22, 2020

spidercrab said:
Does alkalinity actually have any effect on our coral? It seems every article or comment I read is about testing alkalinity and extremely tight control. However, I have yet to notice any effect of alkalinity changes on corals over the last 15 years of keeping them. My alkalinity frequently goes from 11 to 7 almost every week and I have never had faster growing coral. Is there really any evidence that alkalinity changes even effect coral at all?

I have 5 tanks and I keep them all as totally separate systems. They range in alkalinity from 7-11dkh any given day. I switch coral between the tanks frequently for pictures, organizing or better lighting and they are open within seconds. The other parameters are pretty well matched such as nitrate/phos, calcium, pH, temperature and salinity.

I also have a nano tank that I drain completely once ever 2 weeks and refill with freshly made saltwater matching just the temperature and salinity. This tank has several SPS species, zoas and LPS. It has grown so full over the last 5 years that I can no longer put my hand in it. At the time of changing it today the alkalinity was actually tested at 5.5dkh! I drained all of the water and refilled it with a fresh 5 gallons of saltwater at 11 dkh and within 1 minute everything is completely open as if nothing happened. That is a change of 5.5 dkh instantaneously with no effect at all and proven for over 5 years.

I am just curious if anyone else has similar experience or doubts about alkalinity monitoring.

Have you had any instances of coral mortality at all?
I expect your calcium is all over the place as well?

ScottR · Jan 22, 2020

Alk can swing and you can keep alk at different places. But I can say with proof, a high alk swing in a day or two can blanch the tips of SPS. Too high of alk as well will keep acros at bay. With that said, my tank swings from 6ish-9ish albeit slowly. Nothing noticeable from these swings.

spidercrab · Jan 22, 2020

Scrubber_steve said:
Have you had any instances of coral mortality at all?
I expect your calcium is all over the place as well?

I have yet to lose a single coral in the nano tank. This tank does not have fish so it does stay relatively clean. Once a month I will add some reefroids. I do not test calcium in it but I am sure it drops a lot during the 2 weeks.

spidercrab · Jan 22, 2020

ScottR said:
Alk can swing and you can keep alk at different places. But I can say with proof, a high alk swing in a day or two can blanch the tips of SPS. Too high of alk as well will keep acros at bay. With that said, my tank swings from 6ish-9ish albeit slowly. Nothing noticeable from these swings.

Yes but I believe the damage you are seeing from the effect of a change in pH which would occur from dosing. When I do a 100% water change the pH is matched but the alkalinities are far different.

spidercrab · Jan 22, 2020

Terri Caton said:
This is very interesting. Have you noticed any changes in inverts? Do you keep Softies, LPS or anemones?

I keep softies, LPS and SPS. Anemones are too big for a tank this small IMO. I have kept inverts for years and lost a few but they usually live for a long time. If the salinity and temperature arent matched almost perfect it stresses them out quite a bit. I lost a few that way.

Dana Riddle · Jan 22, 2020

BTW, I'm not recommending big swings of any parameters. In my experience, I didn't see widespread bleaching/mortality with alkalinity swings. On the other hand, I've heard some Acropora specimens (such as Walt Disney) are sensitive to alk shifts.

spidercrab · Jan 22, 2020

krash7172 said:
I've been surprised that ppl are keeping what I consider to be low alk tanks. Where should we be? SPS, LPS, Softies?

Edit: I'm 10-11 dkh softies and LPS

That is quite high compared to the ocean levels.

VA5 · Jan 22, 2020

I had a recent near tank disaster two weeks ago that is on point to this convo.
I did 2-3 hours of tank work where I shut down the pump. All looked good and I went out for an hour. When I returned I did a quick check under the tank and noticed the 1500ml of alk reagent (B Ionic) was nearly empty. I had just topped it off before my maintance. For reference my tank is 375 gallon with 50 gallons sump.
When I measured alk it was off the charts of my Red Sea test kit. It took twice as must reagent as a normal test to get a color change at the highest value of 14 dkh.
Looking back I think my sump water level reached the tubes the reagent is dosed from and the alk reagent continued to leach into the water while the Ca reagent formed a precipitate to prevent leaching.
I quickly researched the situation and decided to add vinegar to bring down the alk. I only brought it down to where the test kit finally registered a change with the usual reagent (around14 dkh).
Anyway I was expecting to certainly loose my shrimp, likely my clam and a bunch of corals. The results thankfully was zero loses of any kind. Shutting down the dosing of alk and daily testing resulted in a normal value of 10.5 dkh for my tank within a few days where I started dosing back up.
In general I am a big believer in keeping constant water parameters that are reasonable (meaning not chasing certain numbers). This event surprised as I expected heavy loses from a swing of likely at least 6 alk points in a short period of time. I’m also confident that a swing in the other direction would have caused a major crash.
Just thought this fit the conversation at hand.
As a last comment I would make sure your dosing lines are above any possible water level your sump can achieve .

spidercrab · Jan 22, 2020

VA5 said:
I had a recent near tank disaster two weeks ago that is on point to this convo.
I did 2-3 hours of tank work where I shut down the pump. All looked good and I went out for an hour. When I returned I did a quick check under the tank and noticed the 1500ml of alk reagent (B Ionic) was nearly empty. I had just topped it off before my maintance. For reference my tank is 375 gallon with 50 gallons sump.
When I measured alk it was off the charts of my Red Sea test kit. It took twice as must reagent as a normal test to get a color change at the highest value of 14 dkh.
Looking back I think my sump water level reached the tubes the reagent is dosed from and the alk reagent continued to leach into the water while the Ca reagent formed a precipitate to prevent leaching.
I quickly researched the situation and decided to add vinegar to bring down the alk. I only brought it down to where the test kit finally registered a change with the usual reagent (around14 dkh).
Anyway I was expecting to certainly loose my shrimp, likely my clam and a bunch of corals. The results thankfully was zero loses of any kind. Shutting down the dosing of alk and daily testing resulted in a normal value of 10.5 dkh for my tank within a few days where I started dosing back up.
In general I am a big believer in keeping constant water parameters that are reasonable (meaning not chasing certain numbers). This event surprised as I expected heavy loses from a swing of likely at least 6 alk points in a short period of time. I’m also confident that a swing in the other direction would have caused a major crash.
Just thought this fit the conversation at hand.
As a last comment I would make sure your dosing lines are above any possible water level your sump can achieve .

Yup this is what has lead everyone to believe that Alk must be closely monitored but this is actually a pH swing scenario. Maybe the vinegar dropped the pH fast enough to prevent any major issues.

Dennis Cartier · Jan 22, 2020

spidercrab said:
I have yet to lose a single coral in the nano tank. This tank does not have fish so it does stay relatively clean. Once a month I will add some reefroids. I do not test calcium in it but I am sure it drops a lot during the 2 weeks.

Any chance you could post a FTS of your nano? I searched your threads but did not see any that sounded like a tank thread. I am setting up some simple pico jars and would be interested in seeing what you have managed to keep in your nano using simple techniques.

Dennis