Best method to maintain Alkalinity and Calcium ratio?

[Tim Olson]

I've been struggling the last couple of months to keep my Alkalinity steady and at the right level. I'm also trying to figure out why my hard corals are not doing well at all and if the Alkalinity swings are what's causing the problem. I've been researching all along the way and have learned enough to know that I still have a lot to learn.

Here are my current parameters for my 40g DT as of an hour ago:

• Alkalinity - 137 ppm (yesterday it got down to 114 ppm, but has been as high as 180 when I was dosing)
• Calcium - 400 ppm (370-400)
• Magnesium - 1385 ppm (trying to keep above 1400 to help with Green Hair Algae)
• Temp - 79°
• pH - 8.26 (8.1-8.3)
• Salinity - 1.025
• Nitrates - 1 ppm (usually 0-1)
• Phosphates - 0.00 (using GFO to keep it low to help with GHA)

Other info:

• Dose 30 ml of vinegar a day (5 ml 6 times a day)
• Dose 500 ml of saturated Kalkwasser a day (50ml 10 times a day)
• Not dosing Alkalinity right now (was dosing for a few months, but I quit since I thought it might be hurting the corals)
• I moderately target feed frozen Mysis, Nutramar Ova and Roti Feast 3 times a day.

So, I hope you all can find what I'm doing wrong and some suggestions to get it right.

Thank you

 

[Randy Holmes-Farley Verified Community Expert]

The dosing is with a doser? Or an ATO?

How do you mix the limewater?

The timing of the measurements and dosing is what?

Assuming the dosing is well spread out and you measure at the same time every time, the alk should either be stable or slowly rising or falling, not jumping around. If it is jumping, perhaps it is test error.

 

[Tim Olson]

The dosing is with a doser? Or an ATO?

How do you mix the limewater?

The timing of the measurements and dosing is what?

Assuming the dosing is well spread out and you measure at the same time every time, the alk should either be stable or slowly rising or falling, not jumping around. If it is jumping, perhaps it is test error.

All the dosing is done with dosing pumps, including the Kalkwasser. I mix 1 gallon of water, in a jug, with 2 teaspoons of powder and swirl it until it's clear.

The timing of the dosing is:
• Vinegar

5ml 10am
5ml 11am
5ml noon
5ml 1pm
5ml 2pm
5ml 3pm​

• Kalkwasser (I just raised it today to 600ml/day)

60ml 5pm
60ml 7pm
60ml 9pm
60ml 11pm
60ml Midnight
60ml 1am
60ml 3am
60ml 5am
60ml 7am
60ml 9am
​

On your 3rd point, I've been using my Hanna checker, but I don't do it at the same time every day ... could that be the problem?

Thanks Randy!

 

[JimWelsh]

On your 3rd point, I've been using my Hanna checker, but I don't do it at the same time every day ... could that be the problem?

Yes.

 

[Tim Olson]

Thank you Jim!

I can't believe I didn't realize that before. I'm really in-tune with my pH going up and down during the day, but I never connected to dots with Alkalinity.

All the best!

 

[Randy Holmes-Farley Verified Community Expert]

All the dosing is done with dosing pumps, including the Kalkwasser. I mix 1 gallon of water, in a jug, with 2 teaspoons of powder and swirl it until it's clear.

The timing of the dosing is:
• Vinegar

5ml 10am
5ml 11am
5ml noon
5ml 1pm
5ml 2pm
5ml 3pm​

• Kalkwasser (I just raised it today to 600ml/day)

60ml 5pm
60ml 7pm
60ml 9pm
60ml 11pm
60ml Midnight
60ml 1am
60ml 3am
60ml 5am
60ml 7am
60ml 9am
​

On your 3rd point, I've been using my Hanna checker, but I don't do it at the same time every day ... could that be the problem?

Thanks Randy!

When dosing all the alkalinity at night (as you are), the alkalinity will steadily fall through the other hours, from 9 am to 5 pm. That might explain the differences.

 

[Tim Olson]

When dosing all the alkalinity at night (as you are), the alkalinity will steadily fall through the other hours, from 9 am to 5 pm. That might explain the differences.

Thanks Randy!

Should I does Alkalinity throughout the 24 hour period, like every hour? My current dosing strategy is to offset the pH drop during the night with Kalkwasser and dose Vinegar during the day when pH is naturally higher. Am I making this too complicated or dosing wrong?

 

[Randy Holmes-Farley Verified Community Expert]

There's a trade off to dosing limewater at night (to offset the low pH) and during the day (when most alk demand appears to be taking place.

Dosing day and night might split the difference, but I can't be sure what is best.

 

[Tim Olson]

There's a trade off to dosing limewater at night (to offset the low pH) and during the day (when most alk demand appears to be taking place.

Dosing day and night might split the difference, but I can't be sure what is best.

Sounds like a good plan. I'll dose limewater every hour and see if it helps. Also, I just checked alk (at 12:30pm) and it was 148ppm. I'll always check it at that time from now on.

On another note, my pH has been running 8.3+ during the day, so I'm thinking about deactivating my CO2 scrubber (sodalime) to keep pH below 8.4.

Thanks again!

 

[Randy Holmes-Farley Verified Community Expert]

Sounds like a good plan. I'll dose limewater every hour and see if it helps. Also, I just checked alk (at 12:30pm) and it was 148ppm. I'll always check it at that time from now on.

On another note, my pH has been running 8.3+ during the day, so I'm thinking about deactivating my CO2 scrubber (sodalime) to keep pH below 8.4.

Thanks again!

You're welcome.

It won't hurt for the pH to be up to at least 8.55, but its a waste of money for the scrubber media unless fast coral growth is an very important goal.

 

[Tim Olson]

Excellent! I'll decommission it today.

 

[BlennyKravitz]

Yes.

This is VERY important! also, don't test around feeding time either. Won't affect alk/Ca readings, but will throw off your phosphate and nitrate measurements.
Always test at the same time. I do it in the morning before the lights come on because I assume that's when my alk readings are the highest.

 

[Tim Olson]

Thanks!

 

[Luke Schnabel]

I've been using a BRS Soda Ash that I dose every two hours on the even hours... (12:00..2:00..4:00 etc) It's dosed right in front of an MP40 powerhead

I also dose BRS Calcium Carbonate one every odd hour (1:00.. 3:00.. 5:00 etc)

I split that out to give each dose a full hour to mix into my tank. I've really gotten my levels dialed in. I only test once a week now. If your going to be adjusting your dosing or changing something I would reccomend doing at least 3 tests a week to know what your doing.

 

[Forsaken77]

Thanks Randy!

Should I does Alkalinity throughout the 24 hour period, like every hour? My current dosing strategy is to offset the pH drop during the night with Kalkwasser and dose Vinegar during the day when pH is naturally higher. Am I making this too complicated or dosing wrong?

You could try a Macro Algae Reactor to offset the Ph swing naturally instead of chemically. Because when the lights are off, algae in the DT is using oxygen, causing your Ph to drop. Is you set a reactor to be on a reverse photo period, then it should balance out the Ph swing at night.

 

[Luke Schnabel]

@Forsaken77 Not exactly that but your on the right track. Plants use light and carbon dioxide, the end result is oxygen.

pH in your tank is a direct correlation of carbon dioxide in your water. So if you can keep photosynthesis going at night as well it will offset your drop in pH.

 

[Tim Olson]

I've been using a BRS Soda Ash that I dose every two hours on the even hours... (12:00..2:00..4:00 etc) It's dosed right in front of an MP40 powerhead

I also dose BRS Calcium Carbonate one every odd hour (1:00.. 3:00.. 5:00 etc)

I split that out to give each dose a full hour to mix into my tank. I've really gotten my levels dialed in. I only test once a week now. If your going to be adjusting your dosing or changing something I would reccomend doing at least 3 tests a week to know what your doing.

Great suggestion ... I think I'm still a long way from getting my levels dialed in, since the tank's still pretty young (7.5 months) plus I still have a lot to learn. Therefore, I'll plan on testing as frequently as possible, hopefully 3-5 days a week.

Also, I dose Kalk and Vinegar into my sump's return pump section. I hope that's OK.

BTW, I enter my parameters, and other information, into an MS Access database, so I can track them over time. It's not nearly as much data as using APEX, but it works for now. Hopefully there's a Controller in my future.

Thanks for the help!

 

[Tim Olson]

You could try a Macro Algae Reactor to offset the Ph swing naturally instead of chemically. Because when the lights are off, algae in the DT is using oxygen, causing your Ph to drop. Is you set a reactor to be on a reverse photo period, then it should balance out the Ph swing at night.

@Forsaken77 Not exactly that but your on the right track. Plants use light and carbon dioxide, the end result is oxygen.

pH in your tank is a direct correlation of carbon dioxide in your water. So if you can keep photosynthesis going at night as well it will offset your drop in pH.

I had a refugium in my last tank setup and it did help with pH swings and algae control, since I left the grow light on during the night. Although, I haven't figured out how I can make room for a fuge in my current setup. It's an acrylic tank/base and the base is very cramped, so I'd have to setup and external fuge/sump. Maybe down the road.

Thank you both!

 

[Cory]

Im dosing via my ghl limewater. I dose 500 ml a day. Alk is steady at 8.5dkh. I wont use another method this way is so easy.

 

[Randy Holmes-Farley Verified Community Expert]

@Forsaken77 Not exactly that but your on the right track. Plants use light and carbon dioxide, the end result is oxygen.

pH in your tank is a direct correlation of carbon dioxide in your water. So if you can keep photosynthesis going at night as well it will offset your drop in pH.

I think he was suggesting (correctly) that at night, the algae in the refugium produces CO2 and makes the drop worse (assuming it isn't an offset photoperiod). You are also correct that when lit it consumes CO2.