Cant keep up with my Alkalinity needs - help

[Donavon]

Every tank is different, learning the needs and balance of each set up is a challenge. My current conditions are no different. This set up is challlenging to say the least.
I can’t keep up with the alkalinity needs of this set up and it is driving me nuts. I can’t seem to get the alkalinity to rise above 6.7-7.0 no matter how much I am dosing. If If I dose more it takes more and eventually falls back to that 6.8-7.0 Mark.
Phosphate is typically .04
Nitrates are very low typically undetectable to about .25
My magnesium is staying high @ ~1350
My calcium is staying around 420-450
I have historically kept my alkalinity around 8-8.5, but can’t manage to get above 7 and it’s got me worried about long term effects of stony corals.

I have more coralline algae in this tank than any set up I’ve had in the past and Im wondering if it is just being such a hog that I haven’t found the sweet spot yet. It doesn’t seem right though because My Calcium needs don’t seem to be increasing as the Alk is. They should stay at a similar need as my experience has been over the years.

I have read that nitrate levels can have an effect on alkalinity needs but I don’t understand how that jives.
The system has a total water volume of about 150 gallons, I have Chaeto in my sump, run a protein skimmer, and do a 10 gallon water change almost every weekend.
Lighting is 8 bulb T-5
Plenty of fish, snails, hermits, shrimps and crabs
The only nuisance algae I have is this red filimentaceous stuff that looks like red velvet (nothing I have found will eat it)
I’m looking for any suggestions, explanations, or insight based on experience that might help me figure this out.
Please let me know your thoughts as I am one parameter away from figuring this tank out.

 

[mdb_talon]

Unless you are specifically dowing nitrate my understanding is it has no real impact on alk unless the numbers are fluctuating either up or down a considerable amount.

Curious how much you are dowing daily and what size tank?

 

[ApoIsland]

Every tank is different, learning the needs and balance of each set up is a challenge. My current conditions are no different. This set up is challlenging to say the least.
I can’t keep up with the alkalinity needs of this set up and it is driving me nuts. I can’t seem to get the alkalinity to rise above 6.7-7.0 no matter how much I am dosing. If If I dose more it takes more and eventually falls back to that 6.8-7.0 Mark.
Phosphate is typically .04
Nitrates are very low typically undetectable to about .25
My magnesium is staying high @ ~1350
My calcium is staying around 420-450
I have historically kept my alkalinity around 8-8.5, but can’t manage to get above 7 and it’s got me worried about long term effects of stony corals.

I have more coralline algae in this tank than any set up I’ve had in the past and Im wondering if it is just being such a hog that I haven’t found the sweet spot yet. It doesn’t seem right though because My Calcium needs don’t seem to be increasing as the Alk is. They should stay at a similar need as my experience has been over the years.

I have read that nitrate levels can have an effect on alkalinity needs but I don’t understand how that jives.
The system has a total water volume of about 150 gallons, I have Chaeto in my sump, run a protein skimmer, and do a 10 gallon water change almost every weekend.
Lighting is 8 bulb T-5
Plenty of fish, snails, hermits, shrimps and crabs
The only nuisance algae I have is this red filimentaceous stuff that looks like red velvet (nothing I have found will eat it)
I’m looking for any suggestions, explanations, or insight based on experience that might help me figure this out.
Please let me know your thoughts as I am one parameter away from figuring this tank out.

I don't think corals will suffer with an ALK level in that range. I have run a mixed reef for years where levels routinely get down around the 4 to 5dkh range for weeks at a time.

 

[Donavon]

I am dosing 20 mil every hour on the hour
The alk mix is 4 tablespoons of baking soda per gallon of water
The water volume is around 150-160

 

[mdb_talon]

I am dosing 20 mil every hour on the hour
The alk mix is 4 tablespoons of baking soda per gallon of water
The water volume is around 150-160

That does sound like a lot to not see a change in calcium over a period of time. I would definetely confirm your alk number that it is correct with another test.

 

[Lavey29]

What is your PH? That will affect alk.

 

[ApoIsland]

I am dosing 20 mil every hour on the hour
The alk mix is 4 tablespoons of baking soda per gallon of water
The water volume is around 150-160

If my calculations are accurate that doesn't seem to be much dosing. It's only half a tablespoon per day of baking soda correct?

3785 ml per gallon.
20ml x 24 hours = 480 ml per day
480/3785 = .13
.13 x 4 tablespoons = 0.5 tablespoons per day.

over 150 gallons that's almost nothing.

 

[Donavon]

That does sound like a lot to not see a change in calcium over a period of time. I would definetely confirm your alk number that it is correct with another test.

Good suggestion, I’ll order another test kit and see how they compare, thanks

 

[Donavon]

What is your PH? That will affect alk.

Good question, I haven’t checked PH in quite a long time. I’ll test this tomorrow and repot back
How does the PH affect Alk? If the PH is low will The Alk be unstable?
I quit chasing PH a long time ago, my tank has historically been on the low end (just below 8 Ibelieve)
It’s never caused an issue in the past

 

[Donavon]

If my calculations are accurate that doesn't seem to be much dosing. It's only half a tablespoon per day of baking soda correct?

3785 ml per gallon.
20ml x 24 hours = 480 ml per day
480/3785 = .13
.13 x 4 tablespoons = 0.5 tablespoons per day.

over 150 gallons that's almost nothing.

Hmmm, maybe not much, compared to the previous needs of my tank it is right in line.
But the way I have it set up now the whole tank acts different.
I removed the deep sand bed and ever since have a much bigger need for Alk? Would that make sense?
The coraline algae is easily twice as aggressive that before. That could be the big suck.

 

[Grumblez]

Good question, I haven’t checked PH in quite a long time. I’ll test this tomorrow and repot back
How does the PH affect Alk? If the PH is low will The Alk be unstable?
I quit chasing PH a long time ago, my tank has historically been on the low end (just below 8 Ibelieve)
It’s never caused an issue in the past

PH and Alk are linear. So if PH drops alk Drops. That's why it's almost impossible to have PH below 7.8

 

[ApoIsland]

Hmmm, maybe not much, compared to the previous needs of my tank it is right in line.
But the way I have it set up now the whole tank acts different.
I removed the deep sand bed and ever since have a much bigger need for Alk? Would that make sense?
The coraline algae is easily twice as aggressive that before. That could be the big suck.

Interesting. I'm not smart enough to offer an opinion as to why it needs more but I can tell you that based on that nice dosing calculator

http://reef.diesyst.com/chemcalc/chemcalc.html

you would need 0.3 ounces of baking soda to just to increase alk from 7 to 7.5dkh in 150 gallons of water. I think 0.3 ounces comes out to about 0.6 tablespoons which is more than what you are adding now.

So you are spreading a less than 0.5 dkh increase out by 24 hours is the reason you can't raise it. Not uncommon at all for reef tanks to consume much more than that.

Also - you really don't need to spread the dose that way if you are adding such small amounts. Can just mix the 1/2 tablespoon all at once in a glass of water and dump it in all at once. Maybe do that twice a day and see what happens. I was doing it 3-4 times per day with no ill effects.

 

[Lavey29]

Good question, I haven’t checked PH in quite a long time. I’ll test this tomorrow and repot back
How does the PH affect Alk? If the PH is low will The Alk be unstable?
I quit chasing PH a long time ago, my tank has historically been on the low end (just below 8 Ibelieve)
It’s never caused an issue in the past

Try Google ' How does PH affect alk in a reef tank". You will see some interesting coralations.

 

[Lavey29]

PH and Alk are linear. So if PH drops alk Drops. That's why it's almost impossible to have PH below 7.8

So the poster above stating he has run a mixed reef tank successfully for years with 4 to 5DKH? Does he have a 5 PH to?

 

[rhostam]

Good question, I haven’t checked PH in quite a long time. I’ll test this tomorrow and repot back
How does the PH affect Alk? If the PH is low will The Alk be unstable?
I quit chasing PH a long time ago, my tank has historically been on the low end (just below 8 Ibelieve)
It’s never caused an issue in the past

Chemistry And The Aquarium: The Relationship Between Alkalinity And pH

Randy answers many questions in this complex relationship.

reefs.com

 

[Donavon]

Interesting. I'm not smart enough to offer an opinion as to why it needs more but I can tell you that based on that nice dosing calculator

http://reef.diesyst.com/chemcalc/chemcalc.html

you would need 0.3 ounces of baking soda to just to increase alk from 7 to 7.5dkh in 150 gallons of water. I think 0.3 ounces comes out to about 0.6 tablespoons which is more than what you are adding now.

So you are spreading a less than 0.5 dkh increase out by 24 hours is the reason you can't raise it. Not uncommon at all for reef tanks to consume much more than that.

Also - you really don't need to spread the dose that way if you are adding such small amounts. Can just mix the 1/2 tablespoon all at once in a glass of water and dump it in all at once. Maybe do that twice a day and see what happens. I was doing it 3-4 times per day with no ill effects.

Thanks for the help, I was afraid to do too much at a time. And I had not really done the math correctly.

 

[mdb_talon]

PH and Alk are linear. So if PH drops alk Drops. That's why it's almost impossible to have PH below 7.8

Try Google ' How does PH affect alk in a reef tank". You will see some interesting coralations.

These are not accurate statements. A drop in PH does not cause a drop in alkalinity. A drop in alkalinity can cause a drop in PH but not the other way around.

 

[Grumblez]

So the poster above stating he has run a mixed reef tank successfully for years with 4 to 5DKH? Does he have a 5 PH to?

Linear in the sense that raising one raises the other but they aren't 1:1.

 

[Donavon]

So the poster above stating he has run a mixed reef tank successfully for years with 4 to 5DKH? Does he have a 5 PH to?

Good to know, I probably shouldn’t worry too much about the PH then. Just get the Alk in line.
Guys told me years ago not to chase PH and ever since I haven’t
I probably check PH every 3 months or so. I alway throw out the test kit well before it is used up due to expiration

 

[ApoIsland]

Thanks for the help, I was afraid to do too much at a time. And I had not really done the math correctly.

I didn't do the math correctly my first time either. I errored in the opposite direction you did though and I'm amazed I didn't crash the tank.

I was supposed to add 1.5 - 2 dkh per day but instead was adding 3-4 dkh per day. Went from 5.5 to 17.5 in the course of 2 weeks. Amazed nothing died. So lucky I had a morning free and decided to just run an alk test to kill some time. I think another week of going at the rate I was and it would have been disaster.