PH Levels

[Piazzon12]

Now that I have a fancy pants controller, I can actually see my PH levels. I top off kalk full time, and my PH swings from 8.0 to 8.5 each day.
Looking for opinions... is 8.5 too high or the range too big?
My corals don't seem to mind, but there are a few corals I suspect are less tolerant than others.

 

[Conesus_Kid]

Adam,

How is the kalkwasser topoff delivered? Steadily throughout the day/night, or do you dump it in at once?

 

[Gary Majchrzak]

I wish I had your "problem"

you should be ok- just make sure to be extra careful when adding anything that might raise pH even further.

 

[Piazzon12]

I have float switches hooked to an aqualifter hooked to a 18 Gallon rubbermaid filled with kalk water. Top off is added slowly throughout the day/night as the water level falls. I'd guess it only adds a 1/2 cup at a time, each time it kicks on.
I'm using un-baked alk two part so that lowers the ph when added.

 

[Gary Majchrzak]

what's your alkalinity at? Calcium?

 

[mr.maroonsalty]

It might become a problem when warmer weather brings open windows and lower indoor CO2 levels.

 

[Gary Majchrzak]

pH 8.4 - 8.6 is fairly common and acceptable but rarely does anyone ever hear of a higher pH unless something is going amiss....

 

[Piazzon12]

Mg at 1500
calcium 450-475
Alk targeted at 3 meq/lt

8.5 pH was an open window day last week that set off my alarm (alarm was originally set at 8.5 now its 8.6)

I am to the point now where kalk doesnt keep up with demand, so I'm adding about a cup each of two part every three days... although I seem to use alk faster.

 

[Gary Majchrzak]

it sounds like corals are growing well if kalk isn't keeping up with demand...

don't get caught up in the numbers game. Do your corals appear to be doing well?

 

[Piazzon12]

That's what I figured... everything has been doing great, with the exception of a declining red birdsnest and green/red acro that just won't grow...however that could very well be due to other conditions

 

[tmz]

8.5 is ok but close to precipitation territitory (monitors and test kits can be off)
particularly when adding alkalinity even bicarbonate(unbaked baking soda). Are you seeing any on pumps ,heaters,etc.? It might account for the alk depletion. The diurinal swing is not a worry at 8.0. Be careful not to bounce the alk around it can lead to stn issues, in my experience. PO4? Using GFO?

FWIW, I use just kalk for all top off at about 1.5 tsp per gallon saturation and it meets all the needs in my system which is sps loaded. I had been using a calcium reactor for a couple of years along with it but alk was too high with the lower nutrient levels I
have now.. I haven't needed any supplement other than the limewater for over a year. I get coraline growth too ;not very heavy but corals grow well. Ph 8.21 to 8.38, alk 9.6dkh, calcium 540ppm, mag 1400ppm. Caoralife salt, water changes 1% daily plus maintenance for a total of about 45% per month.

 

[Piazzon12]

I'm not seeing any precipitation at all, thankfully, but at the current growth rates I'd believe it was the corals/clams/coraline utilizing the kalk. The pH probe is newly calibrated as I just got the controller 3 weeks ago and immediately calibrated it. My system is very heavily stocked SPS. I run carbon, but stopped running GFO ~3 months ago when I started low level Vodka dosing. I ramped up to 3.5ml vodka per day and it's keeping my nitrates/phosphates in check. Nitrates < 10 and phosphate at the lowest detectable level (0.01?) of my red sea kit. I realize the kits arent great, but the levels are greatly reduced from where I started. I was fine with lime water for over a year but recently getting all my parameters in check has caused growth to increase, dramatically in some cases. Evaporations rates slow a bit in the spring/fall so my two part addition will vary I'm sure.

 

[tmz]

Ok sounds good. FYI andFWIW
I've been dosing vodka 26ml and vinegar( 1/8th as strong ans vodka in terms of carbon dosing) 60ml(per 550 gallons per day) with a small amount of gfo in pl;ay which hasn't needed a change in 2months. NO3<0.2ppm per salifert, PO4 .04ppm per hanah colorimeter ,udetectable per salifert.

BTW calcium carbonate( coral skeleton) can begin to dissolve at around 7.7 or less; 8.6/.7 will trigger a biotic precipitation,. These conditions vary a bit depending on alkalinity.

While the swing itself is not a worry, there may be reason for concern at night as to the cause for the .5 drop. There may be some hypoxic conditions in the tank during non photosynthetic periods. You may want to consider a macro algae refugium on opposite photo period.