Kalk PH Drop

rhorn67 · Dec 17, 2015

I started dosing kalk using BRS doser controlled with a ReefKeeper Lite. I have the doser running every 15 minutes for 30 seconds during my lighting off cycle. Everything I have read is that dosing will cause PH to rise and that's the reason for running it during the lighting off period as when lights are on the PH is at its highest. What I am seeing is that during the dosing time PH actually drops slightly. Example when dosing cycle started PH was at 8.01 and after an hour or so PH was down to 7.93.

I already have troubles keeping PH in the 8-8.1 range and was hoping in addition to keeping my alk/calc stable dosing kalk would keep PH up. Does anyone have any reasons as to why a PH drop rather than an increase?

Alk 10
calc 480
mag 1380

Thank you

Ron

Randy Holmes-Farley · Dec 17, 2015

Limewater (kalkwasser) never causes pH to drop, but if you do not add much, the natural pH drop of the aquarium during that time may still predominate.

How much were you adding to what size tank, and how did you make the limewater?

Adding 1.25% of the total water volume in saturated limewater will boost pH by about 0.6 pH units instantly. It will be less if you spread out the dosing in time. Adding less will produce a proportionally smaller rise.

rhorn67 · Dec 17, 2015

I have a JBJ RL30 with 22 gallons of water. I am using BRS kalk. I mixed 2 teaspoons per 1 gallon.

Randy Holmes-Farley · Dec 17, 2015

How much volume did you dispense in a day? I don't know how fast your doser is.

To make much impact, you'd want to dose at least 500 mL, maybe 1-2 liters per day. But ramping up slowly to be sure you do not overshoot the alkalinity or pH is a good idea.

rhorn67 · Dec 17, 2015

My doser is 1.1 ml per minute. Based on my current settings I am dosing maybe 24-30 ml during the dosing cycle. Based on your recommendations I am dosing no where near enough. I evaporate on average 4 cups a day so even using kalk for top off I would only get 1 liter a day.

What do you think about my kalk mixture? Should I make a stronger mix?

Randy Holmes-Farley · Dec 17, 2015

Your mix is near saturation, so there's no need to change that.

I'd try for 1 cups for a few days and see what that does to alkalinity, which is the limiting factor typically. If after a few days alk is not rising too much, try 2 cups.

rhorn67 · Dec 17, 2015

Will do. Thank you so much for the help.

Randy Holmes-Farley · Dec 17, 2015

You're welcome.

This has a lot more info on limewater:

What Your Grandmother Never Told You About Lime by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2005-01/rhf/index.htm

Good luck.

rhorn67 · Dec 31, 2015

Update - I was able to get my kalk dosing dialed in. I am dosing as much as I can during the lights off cycle and maintaining water level.

PH is running between 8.08 and 8.22 24 hr period
Alkalinity is running around 10.3
Calcium 480-490
Magnesium 1455

Do you think the PH swing is a problem? Also Alkalinity seems high even though from what I read its within the acceptable range.

Randy Holmes-Farley · Dec 31, 2015

The pH swing is fine. The alk is on the high end, but OK unless it is a ULNS tank (ultra low nutrient)

You can always make less potent limewater if you want the alkalinity to drop a bit.

rhorn67 · Dec 31, 2015

Could you define ultra low nutrient tank? I have adjusted my next batch by minus 1/2 tsp of kalk.

Justiful · Dec 31, 2015

rhorn67 said:
Could you define ultra low nutrient tank? I have adjusted my next batch by minus 1/2 tsp of kalk.

I will take a shot at it based on what I read. I am sure Randy will correct me if I am wrong and I will learn something. So what the heck.

In the aquarium hobby it refers to oligotrophic systems where the nutrients are tightly controled. Through a combination of chemical, biological, and nutrient additives. Most often done with combinations of such things as zeolite, purigen, GFO, Matrix Carbon, ext. to remove nutrients, and a careful dosing regime to add them back and maintain them. ULNS take this beyond normal "prevention" and actively seek to maintain as close to 0 nutrient system possible, while dosing micro-nutrients targeted specifically for their aquarium. If they add too much, they have excessive nutrients, too little and they crash.

High good crash.. High good Crash. That is my understanding of how most of these systems end up playing out long term. For most reefers we may fall down the rabbit hole of dosing, for ULNS people they are in constant free-fall trying to avoid hitting the ground. Carbon dosing is like crack from what I understand.

Did I get it right?

rhorn67 · Dec 31, 2015

I certainly am on top of my tank and its nutrient levels but if your definition is indeed correct I am not a ULNS'er lol.

Randy Holmes-Farley · Jan 1, 2016

ULNS typically means nutrients so low that corals have reduced zooxanthellae so low they are near starving. Only certain kits can read that low, but that is less than 0.01 ppm phosphate and less than 1 ppm nitrate.

rhorn67 · Jan 1, 2016

I recently purchased the Hanna phosphorous ULR tester. I've tested after my last two wc and they have read .01 and .03. Is there a nitrate tester to read ULR? I currently use an API kit.

rhorn67 · Jan 9, 2016

Randy Holmes-Farley said:
ULNS typically means nutrients so low that corals have reduced zooxanthellae so low they are near starving. Only certain kits can read that low, but that is less than 0.01 ppm phosphate and less than 1 ppm nitrate.

Randy - My ULR tests continue to read at .01/02. Nitrates are undetectable using the API kit. Can you recommend a more accurate test solution for nitrates?

Randy Holmes-Farley · Jan 10, 2016

rhorn67 said:
I recently purchased the Hanna phosphorous ULR tester. I've tested after my last two wc and they have read .01 and .03. Is there a nitrate tester to read ULR? I currently use an API kit.

There is no checker for nitrate.

I've not tested nitrate for many years, but it seems people use the Red Sea and Salifert nitrate kits OK.

rhorn67 · Jan 10, 2016

Randy Holmes-Farley said:
There is no checker for nitrate.

I've not tested nitrate for many years, but it seems people use the Red Sea and Salifert nitrate kits OK.

I was thinking about the ULNS you mentioned any my alkalinity. Lowering the kalk mixture brought alkalinity down between 9.5-9.7 so that's looking better. I am going to look at another nitrate test kit to see if there is something a little more accurate or precise.