Bolus dosing

[Garf]

A 3 DKH tank, hallelujah;



Note the increase in average DKH, pre and post bolus;

 

[rishma]

Interesting observation from my tank. I changed the dosing rate of kalkwasser (same total volume). Instead of dosing kalkwasser constantly for 15 hours overnight, I reduced the rate for first 12 hours then doubled the rate for the last 3 hours. The goal was to see if if changed my pH (it did not, I think my aeration overwhelms the effect).

Anyway, I made this change about a 3 weeks go. Over this period my alkalinity demand has gone up by 30%.

I kept my total kalkwasser volume the same, and have increased my AFR rate to compensate.

A little off topic but made me think of bolus dosing.

 

[Koleswrath]

Update after a little over a month of bolus dosing baking soda:

-No magical PH increases but I did notice something interesting that I’ll talk more about below.
- slight magical tabletop alkalinity effect. Alk ranges from 9.7 right after dosing to 9.2 right before dosing over 24 hours and I dose 22ml of sodium bicarbonate solution each morning. According to the BRS calculator this should only take 16ml so some of the alk is missing. I use 297g of Baking soda in a 1 gallon milk jug of RODI.
- precipitation of organics is noticeably less since stopping Kalkwasser. My filter roll is far less brown. Are the organics just being skimmed now? Either way I like that the sand bed has less brown dust. No noticed change in PO4/NO3.
- My Valonia aegagropila has stopped aggressively growing. I’ve been scraping it off my rocks every water change for months and I can now just spot pick it here and there. This is a recent change this past week or so. As a side note my PO4/NO3 have hovered near 0.04/2ppm for the last 8 months or so (maintained by daily measured reef roids and ammonia dosing) so this change is unrelated to nutrients. It could just be the natural benthic progression of algae but it seems awful coincidental.

PH
Part of the Bolus method is immediate ramp to 120% of your typical lighting peak for the first couple hours in a day with a slow ramp down to lights out. I did this for the first week and saw the typical expected PH ramp up throughout the day from the respiration of the coral with a drop during the night.
After a couple weeks I raised the 120% to 140% because my lights were always run in the LPS range and I had the room to increase.
This caused a more pronounced ramp and higher PH peak.
Interestingly the lower end of the PH is also higher. It seems it just doesn’t have time to fall as low as it had before. I might keep upping the light intensity every month until I don’t see any more PH increases. This could be a great way to know when your lights are at the most efficient level for coral respiration (which could equate to growth).

All in all there seems to be some benefits to dosing alk (bicarb) all at once with a quick lighting ramp. Importantly, I don’t think you need to use Fauna’s alk supplement or trace elements to realize some of these benefits.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for the update!

- precipitation of organics is noticeably less since stopping Kalkwasser. My filter roll is far less brown. Are the organics just being skimmed now? Either way I like that the sand bed has less brown dust. No noticed change in PO4/NO3.

That might be from the kalk to bicarb switch, unrelated to bolus dosing, or not. :)

- slight magical tabletop alkalinity effect. Alk ranges from 9.7 right after dosing to 9.2 right before dosing over 24 hours and I dose 22ml of sodium bicarbonate solution each morning. According to the BRS calculator this should only take 16ml so some of the alk is missing. I use 297g of Baking soda in a 1 gallon milk jug of RODI.

What size tank are we talking about?

22 mL to boost alk by 0.5 dkH would fit for 31 gallons of actual water volume.

 

[Koleswrath]

What size tank are we talking about?

22 mL to boost alk by 0.5 dkH would fit for 31 gallons of actual water volume.

Actual water volume is 17 gallons. 16 gallon tank with a small sump.

 

[Koleswrath]

hat might be from the kalk to bicarb switch, unrelated to bolus dosing, or not. :)

Very true, simply switching from Kalk to Bicarb would likely see the same results regardless of how its dosed.

 

[Randy Holmes-Farley Verified Community Expert]

Actual water volume is 17 gallons. 16 gallon tank with a small sump.

OK, so it does seem like some alk is unaccounted for by the pre/post dose rise.

How long after dosing did you measure? In particular, was it for sure long enough to mix in fully?

 

[Koleswrath]

How long after dosing did you measure? In particular, was it for sure long enough to mix in fully?

It was 45 minutes or so. I wanted to make sure it was completely mixed.

 

[Randy Holmes-Farley Verified Community Expert]

OK, thanks. :)

 

[rishma]

I am wondering about this organic precipitation. I have always dosed kalk. I have detritus, but it’s normal to me because I know nothing else.

If I wasn’t dosing Kalk, what would happen to these organics? They would stay in the water? I precipitation good or bad? I doubt we have the answer to these questions but I am having a hard time thinking the flocculant effect is a bad thing. Seems like some bolus advocates imply it’s good.

 

[Koleswrath]

If I wasn’t dosing Kalk, what would happen to these organics? They would stay in the water? I precipitation good or bad? I doubt we have the answer to these questions but I am having a hard time thinking the flocculant effect is a bad thing. Seems like some bolus advocates imply it’s good.

Great question. My worry is that many of the organics get precipitated and bound onto aragonite surfaces like live rock and sand and become locally available to algae or cyano through some mechanism. @Randy Holmes-Farley is this a possibility?

Maybe it's just phosphate that this happens to which may spur the growth of algae.

Anecdotally, along with a decrease of growth of an aggressive Valonia species I've noticed less Cyano growth in my sandbed after eliminating Kalkwasser dosing (noticed after about a month of ceasing Kalk).
I've also heard Adam from Frag garage mention a decrease in Algae in the system he has been trying bolus in after stopping Kalkwasser as well as Mike Paletta who reports the same thing.

 

[rishma]

Great question. My worry is that many of the organics get precipitated and bound onto aragonite surfaces like live rock and sand and become locally available to algae or cyano through some mechanism. @Randy Holmes-Farley is this a possibility?

Maybe it's just phosphate that this happens to which may spur the growth of algae.

Anecdotally, along with a decrease of growth of an aggressive Valonia species I've noticed less Cyano growth in my sandbed after eliminating Kalkwasser dosing (noticed after about a month of ceasing Kalk).
I've also heard Adam from Frag garage mention a decrease in Algae in the system he has been trying bolus in after stopping Kalkwasser as well as Mike Paletta who reports the same thing.

Interesting. I cannot imagine how kalkwasser could cause more algae. I believe algae pulls nutrients from the water.

 

[Randy Holmes-Farley Verified Community Expert]

Did you ever look for a pH effect of the switch before initiating the light ramp?

 

[Luminous74]

Great question. My worry is that many of the organics get precipitated and bound onto aragonite surfaces like live rock and sand and become locally available to algae or cyano through some mechanism. @Randy Holmes-Farley is this a possibility?

It is often claimed that limewater (Ca(OH)₂) precipitates phosphate (PO₄). These precipitates could potentially be utilized by algae, as bacteria might be able to dissolve them again. This is presumably due to the creation of a locally acidic microenvironment on the surface of the deposits, allowing algae to access the phosphate once more.

It would be interesting to know whether there is clear and definitive evidence that this mechanism occurs under certain conditions. However, I assume that there are many aquariums using limewater without experiencing algae problems. This could suggest that either the re-dissolution of phosphate does not happen to a significant extent or that other factors—such as the overall availability of nutrients, the bacterial environment, or competition from corals—play a crucial role.

 

[Randy Holmes-Farley Verified Community Expert]

It is often claimed that limewater (Ca(OH)₂) precipitates phosphate (PO₄). These precipitates could potentially be utilized by algae, as bacteria might be able to dissolve them again. This is presumably due to the creation of a locally acidic microenvironment on the surface of the deposits, allowing algae to access the phosphate once more.

It would be interesting to know whether there is clear and definitive evidence that this mechanism occurs under certain conditions. However, I assume that there are many aquariums using limewater without experiencing algae problems. This could suggest that either the re-dissolution of phosphate does not happen to a significant extent or that other factors—such as the overall availability of nutrients, the bacterial environment, or competition from corals—play a crucial role.

I have not seen direct evidence that calcium phosphate precipitates directly, but it might, just like lanthanum phosphate.

But what limewater almost certainly does is accelerate abiotic precipitation of calcium carbonate by boosting pH , and those fresh surfaces will bind phosphate. Maybe it gets buried under more calcium carbonate, or maybe it tends to block further local precipitation. If that effect is significant, then other ways pH is raised, such as a CO2 scrubber) will also do it.

 

[Koleswrath]

Did you ever look for a pH effect of the switch before initiating the light ramp?

If you mean the switch from kalk to bicarb, no, I did not. I imagine it still happened though.

 

[Oldreefer44]

It is often claimed that limewater (Ca(OH)₂) precipitates phosphate (PO₄). These precipitates could potentially be utilized by algae, as bacteria might be able to dissolve them again. This is presumably due to the creation of a locally acidic microenvironment on the surface of the deposits, allowing algae to access the phosphate once more.

It would be interesting to know whether there is clear and definitive evidence that this mechanism occurs under certain conditions. However, I assume that there are many aquariums using limewater without experiencing algae problems. This could suggest that either the re-dissolution of phosphate does not happen to a significant extent or that other factors—such as the overall availability of nutrients, the bacterial environment, or competition from corals—play a crucial role.

Having been on the system 8 plus months and despite having ramped lights up by 80% above what was designated as a mixed reef setting, I have no algae to speak of even with PO4 averaging about 1.2. I have had cyano issues but since cutting back on feeding large amounts of frozen foods it is pretty much gone.
Also didn't have algae issues when dosing kalk and AFR but did have a lot of precipitate which is no longer an issue after switching to Bolus. Still very happy with growth results with no downside that I can think of. Also agree that using FM products is probably not necessary but costs are negligible so why not?

 

[Luminous74]

I have not seen direct evidence that calcium phosphate precipitates directly, but it might, just like lanthanum phosphate.

But what limewater almost certainly does is accelerate abiotic precipitation of calcium carbonate by boosting pH , and those fresh surfaces will bind phosphate. Maybe it gets buried under more calcium carbonate, or maybe it tends to block further local precipitation. If that effect is significant, then other ways pH is raised, such as a CO2 scrubber) will also do it.

Thank you for your response.

Is it definitively possible that these deposits can be locally dissolved by bacteria and thus become available for algae, for example?

In new tanks with artificial rock or sand, it is often observed that they initially bind a lot of phosphate. In many cases, PO₄ is dosed to prevent limitation—until a certain point when the bound phosphate is suddenly released, causing a sharp increase in PO₄ levels.

Is this the same type of deposition? This would mean that, theoretically, dosing limewater could create a similar effect to that seen in a newly set up tank.

Could this explain why some aquariums experience increased algae growth despite very low measured PO₄ levels, while corals simultaneously show signs of nutrient limitation?

 

[Randy Holmes-Farley Verified Community Expert]

Thank you for your response.

Is it definitively possible that these deposits can be locally dissolved by bacteria and thus become available for algae, for example?

In new tanks with artificial rock or sand, it is often observed that they initially bind a lot of phosphate. In many cases, PO₄ is dosed to prevent limitation—until a certain point when the bound phosphate is suddenly released, causing a sharp increase in PO₄ levels.

Is this the same type of deposition? This would mean that, theoretically, dosing limewater could create a similar effect to that seen in a newly set up tank.

Could this explain why some aquariums experience increased algae growth despite very low measured PO₄ levels, while corals simultaneously show signs of nutrient limitation?

Algae can only access a very small amount of phosphate that is bound to the surface of calcium carbonate it is sitting on, not anything buried below the surface. I doubt that spurs noticeably bioavailability of phosphate.

If there are loose deposits of calcium phosphate, that might lead to more accessibility. I’m not sure if that happens, however.

Can algae possibly release phosphate down in pores of rock? Maybe.

I’m just not convinced that phosphate from rock drives a lot of algae problems since many tanks with elevated phosphate everywhere do not have algae problems.

 

[Koleswrath]

I’m just not convinced that phosphate from rock drives a lot of algae problems since many tanks with elevated phosphate everywhere do not have algae problems.

I agree with this to a point. The high phosphate/ high coral load tanks that don’t suffer algae problems likely limit other necessary elements required for rampant algae growth or have other methods of control such as allelopathy.
However, low coral biomass tanks with high phosphate/nitrate levels that don’t have blooms of something seem to be more uncommon.
These low coral mass tanks may be more susceptible to the bound phosphate that could be sunk in liverock.