limewater dosing and C02 scrubber questions

[jason2459]

The main question for this thread is:
Why do I not need my CO2 scrubber now that I've switched from using limewater in my ATO to dosing limewater separately and ATO with fresh RO/DI water?


This is mostly out of curiosity of why something is the way it is currently with my setup.

Recently I've been playing around with a few things both of which are influenced by TMZ.

Technically I'm not dosing as much limewater anymore as my limewater dosing rate is slightly less then the evaporation rate. The limewater is now being dosed every minute for 1 second 24/7 which from what I calculate out to ~1.5 gallons per day.


My new setup and Apex programming can be seen here.
http://www.reefcentral.com/forums/showthread.php?p=24238460#post24238460

But I'll copy paste my last post in that thread showing my graphs in 3 different setups.

And with that above things are stable and awesome. This was all influenced by TMZ.

The ATO kicking in as needed I think just enough but not to much is nice.

But here's some charts I had to pull off the Apex directly as fusion doesn't go back far enough. These show how the CO2 scrubber helped and now with the consistent lime dosing its not needed and protects against one off daily spikes from events where humidity significantly drops.

Here's a graph of my system with using my kalk/lime as ATO no CO2 scrubber. It would dip just under 7.8 regularly at night. It most likely wasn't an issue and I could have continued with that most likely indefinitely

Limewater ATO alone

Edit: fyi those big dips 4 times there are my automated 4x per day feedings where my Apex shuts down my return pump/skimmer and feeds a mix of NLS Marine/AlgaeMax pellets.


But I personally would rather maintain above 8.0 if there's a reasonable and easy way which the CO2 scrubber is. This kept my pH above 8.0 consistently. I picked these dates as it shows what happens when humidity drops a lot and ATO kicks in more. It snowed quite heavily on the 24th here. pH would normally range with this setup between 8.0 and 8.3

Limewater ATO + CO2 scrubber.

Now that I have my ATO and Limewater dosing separate for some reason I do not need the CO2 scrubber and maintain in what I see as about as perfect range as I could be in with little effort of 8.1-8.2. Small swing and I image little to no alk spikes. Alk has maintained at 10 as it has been. The past few days have been perfect as well as its been snowing the past 2 days. So it shows 1 day of no snow and two days with snow with no significant pH spike like there was above on the 24th with limewater as ATO up to 8.5.

Limewater dosing 1s per minute alone. ATO separate. No CO2 scrubber. Snow last two days

My theory is that the constant by the minute dosing is keeping the CO2 levels down much more efficiently then the periodic dosing of using it in the ATO where CO2 can creep back up faster and pushes the overall pH down more in the long run requiring that CO2 scrubber?

 

[bertoni]

Are you dosing on a timer now? The limewater might be entering the tank at a more consistent rate, as you suggest. If the evaporation rate varies a lot throughout the day, the fixed dosing might keep the pH more stable, but induce a bit of salinity swing.

 

[jason2459]

Are you dosing on a timer now? The limewater might be entering the tank at a more consistent rate, as you suggest. If the evaporation rate varies a lot throughout the day, the fixed dosing might keep the pH more stable, but induce a bit of salinity swing.

Yes, its now controlled by my Apex to run for one second every 59 seconds as long as the pH is not above 8.5. Which maintains a dosage under my evaporation rate. So, I'm dosing less lime water per day but attaining much higher and more stable pH all day and night then I was just using lime water in my ATO before adding a CO2 scrubber.

 

[jason2459]

Limewater ATO by itself:
Sub 7.8 to ~8.0 swings daily with periodic spikes due to higher evap rates

Lime water ATO plus CO2 scrubber:
~8.0 to 8.3 swings daily with periodic spikes due to higher evap rates.

Lime water dosed separately under evaporation rate and NO CO2 scrubber:
~8.1-8.2 swings daily with no spikes due to increased evap rates.

 

[bertoni]

Okay, since the limewater is on a timer, I would guess that the tank has great pH stability but lower SG stability.

 

[jason2459]

Okay, since the limewater is on a timer, I would guess that the tank has great pH stability but lower SG stability.

That's possible though would seem extremely minimal. I've got the rate going just under the evaporation rate so the ATO goes off every couple hours. So, I would guess its possible the salinity could be more stable?

 

[bertoni]

I don't know that the change in salinity would be enough to be measurable. You could try a few measurements, if you're worried, but I am not sure that I'd bother.

 

[dkeller_nc]

Honestly, I have a hard time constructing a logical scenario that explains the data you've collected unless there's another effect going on that influences the ATO additions between the dark/light periods in your tank.

Is it possible that you have a automated thermostat that's significantly dialing back the heat at night, such that the humidity in the room that the tank's in goes up, and the ATO is putting considerably less in during the dark hours? If so, that may explain the pH dips to 7.8 when you had the kalkwasser running through your ATO. With your current set-up pumping kalkwasser at a constant rate, it may be that the additions of kalkwasser overnight actually exceed the evaporation rate, though averaged out over a 24 hr. period it's less than the evaporation rate.

 

[jason2459]

I don't know that the change in salinity would be enough to be measurable. You could try a few measurements, if you're worried, but I am not sure that I'd bother.

Nope, I'm not concerned at all enough but my Apex does track the salinity and it's fairly constant as well as it can be considering interference.

Honestly, I have a hard time constructing a logical scenario that explains the data you've collected unless there's another effect going on that influences the ATO additions between the dark/light periods in your tank.

Is it possible that you have a automated thermostat that's significantly dialing back the heat at night, such that the humidity in the room that the tank's in goes up, and the ATO is putting considerably less in during the dark hours? If so, that may explain the pH dips to 7.8 when you had the kalkwasser running through your ATO. With your current set-up pumping kalkwasser at a constant rate, it may be that the additions of kalkwasser overnight actually exceed the evaporation rate, though averaged out over a 24 hr. period it's less than the evaporation rate.

Yes, the temp after 11pm drops to reduce furnace usage. Also, practically my entire system lights, flow direction, flow speed, lunar lights, feedings, and temp are all synchronized to the seasonal chart. So, the temp in the tank also drops at night compared to the day and decreases/increases it's low's and highs.

So, yes that could very well be why the very low dips with out the CO2 scrubber. I wasn't really thinking about that but very good point.

I'm more curious though about before and after switching to the lime dosing vs. lime ato w/ CO2 scrubber. I didn't think I would have this kind impact on pH. I was expecting some pH stability and namely the reduced chance of high spikes due to the higher evaporation rates during winter months mainly when it snows. I wasn't expecting constant increase in pH over 8.0 with out the CO2 scrubber.

I'm not complaining at all because my house is pretty well closed up all year long due to allergies so it's nice to not have to depend on the scrubber to help increase pH.