Advice on pH dilemma, please.

[GlassReef]

Sorry, this is going to be a little long. Please stick with me. :o

I'm trying to win a battle against dinoflagellates in my 375gal. The accepted method seems to be raising pH to around 8.5 and keeping it there for 2 weeks. My normal pH ranges from 8.19, early in the morning, to 8.32 (late afternoon).

I hooked up a kalkreaktor to my ATO so that all evaporated water is replaced with kalkwasser. I then installed a strong fan pointed at the sump to maximize evaporation. The max pH this gave me was 8.39, in the late afternoon.

I decided to bite the bullet and add a slurry (in addition to the kalkwasser) made up of 2 teaspoons calcium hydroxide and a cup of RO water. I poured this into the sump and crossed my fingers. Well, after some experimentation with the amount to dose, I got the pH up to 8.5 - my dilemma is, I can't keep it there.

The 8.5 drops to 8.4 quickly. I can keep the pH up all day by adding the slurry about every 2 hours, but during the night the pH drops rapidly and reaches 8.19 by morning.

So... does anyone have an idea how I can maintain the 8.5 during the night? Also, do you experts think I'm harming anything by adding so much Ca(OH)2 in the form of slurry? All tank inhabitants seem to be fine with it, so far.

TIA

[HighlandReefer]

No matter what you try, you are going to end up raising your alk level through the roof. This will cause calcium carbonate precipitation on your glass, equipment..............etc. :)

You may want to resort to other methods for controlling dinos. Some dinos will flourish at high pH levels, whereas other species can be controlled. It will depend on the species of dinos you have. :(

[GlassReef]

Thanks for the reply. Cliff. Here's what mine look like:

First through the m'scope. I got the pic from a thread here on RC. Looks exactly like mine (author says possibly Prorocentrum lima) ...

http://i515.photobucket.com/albums/t358/selbold/Misc/Dinos.jpg

and in the tank ...

http://i515.photobucket.com/albums/t358/selbold/Misc/Dino-2.jpg

http://i515.photobucket.com/albums/t358/selbold/Misc/Dino-3.jpg

I haven't really experienced any pronounced rise in Alk. It's gone from 8.3 dKH to 9.3 dKH, after 3 days. Does that say anything about tank conditions. My past experience was always that kalk addition would raise Alk - but not this time. I am getting a lot of CaCO3 precipitation. :(

[HighlandReefer]

Based on my microscopic observations of my algae, cyano and dino problems, I believe your problem is not so much dinos, but probably an algae. The algae forms a mat and food source for the dinos which causes the dinos population to increase tremendously. I have observed this to occur in my system. If you get rid of the algae, then IMHO your dino problem will follow suit. I would concentrate on your algae problem by constantly removing all the algae, cyano & dinos intermixed in the mat. Reduce your phosphate & nitrate levels.

[HighlandReefer]

FWIW, that is a weird growth going on. It does not look similar to my observations that occur when dino populations go crazy. :lol:

You have any other pics of your pest?

[HighlandReefer]

Using saturated kalk water to replace your evaporated water will provide the most pH increase. After that you could add dry baked baking soda (sodium carbonate) but you will be shoveling it in and will need to be careful with your pH. I did this myself, but could not get my pH up to 8.5 for very long and could not stand over my tank to constantly do this. I can tell you I went through some sodium carbonate though. :lol:

Edit: The only thing I accomplished was to form a calcium carbonate film around the lower third of my tank glass, which took forever to get rid of. :(

[GlassReef]

I'll get some more pics up in a couple of hours.

Next problem. :confused:

As I mentioned in my first post my Alk normally runs at 8.3. The Kalk dosing had caused it to rise to 9.2, or so - that was last night. I just measured it (LaMotte), its 6.9 !!! What the heck could have caused that. My Ca has remained normal at 440 and my Mg seems to have dropped from 1350 to 1300.

What the heck is going on here???? :(

[HighlandReefer]

For every 1 dkH drop in alk you should get a calcium drop around 7 ppm. 21 ppm calcium would be hard to detect using hobby grade test kits.

[GlassReef]

Thanks, Cliff. Any idea what could have caused such a drop in Alk?

BTW - I posed the question in another thread.

[HighlandReefer]

If your alk reading is actually above 12 dKH, then abiotic precipitation will eat up alk & could account for quite a drop in alk. If your tank occupants are using lots of alk, I have seen some sytems easily use over 2-3 dkH of alk daily. Using hobby grade alk kits do have a considerable error of margin, which can account for some of this. Averaging alk consumption over a week is a much better practice then using daily alk measurements. ;)

[HighlandReefer]

FWIW, you are working within the error of margin for hobby grade alk test kits. :)

[GlassReef]

I suppose the Alk could have gotten above 12 after I tested last evening, when it was 9.2 - I'm just gonna stop with this kalk/high-pH thing. It all just seems too risky.

[Randy Holmes-Farley]

Dosing a lime slurry with a dosing pump could be used to keep the pH a lot higher than clear limewater alone. Maybe put it on a controller to keep the pH from getting too high.

[HighlandReefer]

Lime slurry, I didn't give that a thought. :D

Any guess Randy as to what the pH of a lime slurry would be? :)

[Randy Holmes-Farley]

12.54 at 25 deg C, same as saturated limewater, but it will carry a lot more potential to raise pH when the solids dissolve in the tank. :)

[HighlandReefer]

The slurry would have to be mixed and hand dosed I assume.

It would be nice if this could be automated for additional supplementation for alk and calcium, once kalk water is satruated. I know a calcium reactor. :lol:

[Randy Holmes-Farley]

You could have a stirring bucket of it, with a dosing pump sucking it in and dosing it. :)

[HighlandReefer]

Making sure there is an airtight lid would help reduce abiotic precipitation. This would be the same as using a kalk or calcium reactor as far as contaminates, but would be a much cheaper method. Sounds good to me. :D

[GlassReef]

Thanks guys.

I've been dosing approx. 2 tsps of Ca(OH)2 (in a slurry) every two hours, or so, for the last 36 hours. The pH gets as high as 8.57, but drops back down to 8.4 after almost exactly 2 hours and 20 minutes. I noticed the regularity of the decline while checking the pH graph on my Apex controller.

[HighlandReefer]

You need to use a controller as Randy stated to keep the pH from getting too low or too high. ;)

[GlassReef]

Randy, Cliff - let me see if I understand (thanks for your patience). If I had a sealed (let's say 6") acrylic column with:

- a strong circulation pump hooked to it (and continuously on) to keep the powder completely dissolved/suspended

- RO tubing connections for In/Out (the RO water would be driven by a peristaltic pump hooked to my controller to monitor pH)

I would then drop a bunch of Ca(OH)2 into the reactor. Is that, basically what your describing?

[HighlandReefer]

Stirring enough to keep everything supsended but no more, to help reduce abiotic precipition. If your reactor holds enough for the periods of time you are gone.

[HighlandReefer]

The next question I would have is what is a good recipe for the kalk slurry? :lol:

[GlassReef]

I didn't want to over stay my welcome, Cliff. :o

But, now that you mention it ....

[HighlandReefer]

I know Randy, I am a pain in your back side. :lol:

[HighlandReefer]

If you want to use the reactor to supplement with, I would experiment with the amount of kalk you add. Start with a low amount of kalk and then work your way up, depending on how much it takes to maintain your pH using your controller. The more you add, the more risk of increasing the pH too much using a relatively small volume in a reactor. Perhaps start at around 3-4 teaspoons of kalk per 1 gallon of rodi. ;)

[HighlandReefer]

FWIW, if your controller sticks in the on position, you could dump the entire contents of your reactor tube at one time. I would have plenty of checks and balances going on to prevent overdose. ;)

[GlassReef]

Sounds reasonable. Again, thanks for all the help. :)

[HighlandReefer]

Your welcome. ;)

Let us know how it works out for you. FWIW, I see a possible application doing this in place of a calcium reactor. :D