Kalk vs 2 part

mcarroll · Aug 12, 2015

There's one point I may be confused on.

First what I'm not confused on:

I'm positive you said that an EC meter (or EC/Ph meter...) that will read to about 10.3 would be ideal for this testing.

I see Hanna's "DIST 4" that'll read up to 20mS for $50. Do you think it'd be worth looking for something less expensive, or is this unit not good for any reason? Just looking for some good examples to shop for now...familiar with Hanna from their Checkers I've used. Would like some other options if there are any good ones. $50 isn't unfair, but feels like a lot for a limited-use device if there are more economical options that would be acceptable. Then again, maybe I'll find more than one use for it!

I do have a Reefkeeper port open for one new module if anyone thinks a solution would be better added there...but there's quite a bit more cost, and I can't tell what range/resolution their pH probe is.

Second, I may be confused on what to expect still because of the chart.

FYI, the 5074 reactor is sealed and only mixed lightly at the bottom during pumping. The ATO reservoir is covered, but not tightly, and the water is pumped from the bottom of the reservoir into the reactor.

Since even at the end of a load there's always sediment left. With the chart, are you saying there're always enough hydroxide ions among the sediment to keep the EC pegged at whatever you initially mix it to? If not pegged, how much can I expect the mS to drop between a fresh recharge of lime and when the calcium is essentially gone? How will I know?

Randy Holmes-Farley · Aug 12, 2015

Be careful to distinguish a pH probe from a conductivity probe. To read in mS/cm it must be a conductivity probe. Some units may have both probes in one unit, but that's not too common.

In a reactor, fresh water is constantly coming in that needs to be mixed with the undissolved calcium hydroxide, so such a reactor must be stirred, at least occasionally.

In my setup, and in the data I show in the article, I mix up one large batch of limewater and use it until it is nearly empty, then mix again. So no stirring between making new batches, which might be a week or a month (or a day).

The DIST 4 looks fine for this purpose. The Pinpoint Salinity meter also works well, and need not be handheld for measurement since the probe can dangle into a container by its cord. It would also serve for salinity in the tank while the DIST 4 cannot. A conductivity probe for the reefkeeper would allow salinity monitoring and checking limewater potency.

mcarroll · Aug 13, 2015

Meters
I've noticed seperates and combo units...aren't pH and TDS actually calculations on the EC reading and from the same probe? Aside from $5 eBay units (too good to be true), I haven't found any economical combo-units. Either the Hanna or something pretty similar (HM Digital?) seems to be about the best option.

Reefkeeper
I found the details of that RK pH probe - it claims to read to .01 units. Would this be a sensitive-enough pH probe to work well for this purpose? Mostly only curious on this...RK seems like double-overkill for what I'm trying to do.

The Pinpoint appears to be in the same price-neighborhood as the RK solution, but I admit it would be nice. They are just a bit too pricey to justify.

Tunze 5074
True, this is not a still reservoir and there will always be a gentle stirring at the very bottom of the reactor when it runs. But, I'm not sure this would be similar to a Nilsen reactor in the ways you mention. (Not too many people have actually seen one of these 5074's in action.) There is never crust or the other symptoms you mention, for example.

It will be more interesting to actually know what's happening with an EC meter though - I could definitely be mistaken!! Not knowing the potency of the water my ATO adds kinda sucks. More of the threads that talk about limewater should bring up the use of EC meters...don't think I've run into anyone on forums or in person using one of them outside of some articles. Not for this purpose anyway.

The water-inlet is at the bottom of the 5074, so the force of pumping water is all that stirs it within the sealed container, and it gets swirled very gently. FWIW, I suspect if a Nilsen reactor owner watched my reactor "mix" they'd think it wasn't working.

It also seems like aything "better" than the 5074 would be more costly (like your ReefFiller setup) and/or eat pumps like a typical pump-in-reservoir setup is reputed to. The whole ATO setup I run, inlcuding the 5074 would retail under $250...and it's my ATO.

A single-head ReefFiller is $280 all by itself.

Anyway, if I had excess space I might have considered a plain reservoir just for the simplicity of it, but space is an even taller order than the money...which is a tall order itself.

And if I do go for a ReefFiller I think it would go toward an auto-water-change system before dosing anwyay. (This is under consideration and I think it can be justified!

)

Question
Not in any denial over it, but you left the question opn in the article - how does lime "absorb" impurities without precipitation being involved? I thought from past reading that those impurities (a la the Sr and Mg in the Kalk+2 product out there) were essentially inert.

From the Degredation... article:

"...these solids [at the bottom of the kalk reservoir] also absorb impurities like copper out of the water"

"...impurities would not precipitate on degradation of the limewater..."

Randy Holmes-Farley · Aug 13, 2015

mcarroll said:
Meters
I've noticed seperates and combo units...aren't pH and TDS actually calculations on the EC reading and from the same probe? Aside from $5 eBay units (too good to be true), I haven't found any economical combo-units. Either the Hanna or something pretty similar (HM Digital?) seems to be about the best option.

No. A pH meter is usually a glass bulb that is sensitive to the H+ concentration.

Conductivity passes a high frequency alternating current between two electrodes to get conductivity.

Randy Holmes-Farley · Aug 13, 2015

mcarroll said:
Question
Not in any denial over it, but you left the question opn in the article - how does lime "absorb" impurities without precipitation being involved? I thought from past reading that those impurities (a la the Sr and Mg in the Kalk+2 product out there) were essentially inert.

From the Degredation... article:

"...these solids [at the bottom of the kalk reservoir] also absorb impurities like copper out of the water"

"...impurities would not precipitate on degradation of the limewater..."

Copper in the lime or in the source water will precipitate to some extent as copper hydroxide, but it will also bind to the surface of undissolved calcium carbonate and calcium hydroxide. That is why in the article, adding more solids to the limewater reduced copper even more than just copper in ordinary saturated limewater.

http://www.advancedaquarist.com/2003/5/chemistry

from it:

Consequently, the purification of limewater may not be entirely driven by pH, but also by the presence of “clean” mineral surfaces to which impurities such as copper will adhere.

mcarroll · Aug 13, 2015

Very interesting. (I read nearly all of these articles before I ever set up my tank, but it's been years...almost as good as a first read sometimes! LOL)

So, are you saying that the "relatively pure" molecules created during precipitation in limewater are actually "sticky" (but not atomically so) to some other ions in solution? (You looked at copper. Also, does this stickiness have a name? Just curious to look it up some more.)

At the same time it's also true that "those other ions" do not precipitate themselves? (It took a few tries and relatively extreme measures in your demonstration to get pretty close to all the Cu to precipitate.)

Can we infer from this that while the Ca and alk delivered may be lower in a stirred reactor vs a still one, that it would also be more pure?

It also sounds like dosing the solids of kalkwasser isn't such a great idea..especially if you're on a meager/nonexistent water change plan....and I've seen lots of folks suggest it....tho not many recently.

If one "doses it all", it sounds like the tank could gain some Mg and other ions in the precipitate (along with the rest of the impurities) that are actually useful or "active" once the pH falls a bit and they were processed somehow within the biota of the tank. Speculation, but it's hard to imagine that being impossible...for what that's worth, and not that I'd do it.

Randy Holmes-Farley · Aug 13, 2015

mcarroll said:
Very interesting. (I read nearly all of these articles before I ever set up my tank, but it's been years...almost as good as a first read sometimes! LOL)

So, are you saying that the "relatively pure" molecules created during precipitation in limewater are actually "sticky" (but not atomically so) to some other ions in solution? (You looked at copper. Also, does this stickiness have a name? Just curious to look it up some more.)

Yes, mineral surfaces are sticky to certain other ions That's why, for example, phosphate sticks to calcium carbonate surfaces like live rock, and binders like GFO and aluminum oxide.

This presentation by Frank Millero shows how phosphate binds to calcium carbonate in the ocean:

http://yyy.rsmas.miami.edu/groups/jmc/fla-bay/fbay.html

The process goes by the name adsorption (which implies surface binding only) as opposed to absorption which implies getting inside.

Randy Holmes-Farley · Aug 13, 2015

mcarroll said:
At the same time it's also true that "those other ions" do not precipitate themselves? (It took a few tries and relatively extreme measures in your demonstration to get pretty close to all the Cu to precipitate.)

Can we infer from this that while the Ca and alk delivered may be lower in a stirred reactor vs a still one, that it would also be more pure?

It also sounds like dosing the solids of kalkwasser isn't such a great idea..especially if you're on a meager/nonexistent water change plan....and I've seen lots of folks suggest it....tho not many recently.

If one "doses it all", it sounds like the tank could gain some Mg and other ions in the precipitate (along with the rest of the impurities) that are actually useful or "active" once the pH falls a bit and they were processed somehow within the biota of the tank. Speculation, but it's hard to imagine that being impossible...for what that's worth, and not that I'd do it.

Copper will precipitate as copper hydroxide down to a certain level. But as I showed in the article, you can drive the concentration even lower than that equilibrium process allows by providing solid surfaces to bind the copper.

A stirred reactor isn't necessarily any better if both have solids. My unstirred limewater has lots of solids. But copper MAY be lower in a system with solids than without. The amount of calcium and alkalinity won't be noticeably impacted by this process.

If you dose the solids to the tank, you may be able to use the magnesium in it that will dissolve in the lower pH of the aquarium.

mcarroll · Aug 13, 2015

Randy Holmes-Farley said:
Yes, mineral surfaces are sticky to certain other ions That's why, for example, phosphate sticks to calcium carbonate surfaces like live rock, and binders like GFO and aluminum oxide.

This presentation by Frank Millero shows how phosphate binds to calcium carbonate in the ocean:

http://yyy.rsmas.miami.edu/groups/jmc/fla-bay/fbay.html

The process goes by the name adsorption (which implies surface binding only) as opposed to absorption which implies getting inside.

I think the terms were interchanged in the article a couple times which did make me wonder a little. I'm a little familiar with the concept of adsorption from the use of activated carbon....and I guess I just never thought about GFO much (never had to use it) but that too! I guess I had assumed that great lengths (such as activating carbon) would have to be gone to in order to have it happen at any scale. I really could never imagine live rock having phosphate stuck to us. Gonna check out that presentation now!

Randy Holmes-Farley said:
Copper will precipitate as copper hydroxide down to a certain level. But as I showed in the article, you can drive the concentration even lower than that equilibrium process allows by providing solid surfaces to bind the copper.

A stirred reactor isn't necessarily any better if both have solids. My unstirred limewater has lots of solids. But copper MAY be lower in a system with solids than without. The amount of calcium and alkalinity won't be noticeably impacted by this process.

If you dose the solids to the tank, you may be able to use the magnesium in it that will dissolve in the lower pH of the aquarium.

Got you now!

mcarroll · Aug 13, 2015

In case I'm not the only one that had more trouble than he should have finding the content on that site...here:

The link titled simply: PO4 & Carbonate Interaction gives you the slide view, with controls.

I can give a few spoilers from reading what I've seen so far (reading the rest as soon as I hit "post"):

they mention that the effect is electrostatic but there's a not-understood pH component to the adhesion as well. (Not saying a thing. )
it also says that desorption of phosphate from aragonite is also a fast process (just like sorption) and that it is thought to be a source of PO4 to the water column when sediments are stirred up. Reaching equilibrium with the water in about 10 minutes.
It also looked like this was all about particulate aragonite (sediment) vs rocks or sand.
There's a lot yet unstudied. Iron oxide and organics are mentioned in this regard.
I think I've seen some of material before...but that wavy background is defnitely not familiar!

I've seen what people online go through to "purge" "old" rock....it's not a 10 minute rinsing!

(Reading on!!)

mcarroll · Aug 13, 2015

I'm embarrassed to say that presentation is one of the first things I've read where I wished there were less pictures and more words because I couldn't understand the pictures. I haven't seen that many greek letters since I picked up the wrong Stephen Hawking book at the library!

I definitely got the gist, but a lot of those charts looked like duplicates to me and some seemed to have the same units on both axes.

Here's their summary: (the best part cuz it had all the words!)

This still leaves me with the feeling that PO4 sticking to live rock shouldn't be quite the problem it seems to be for people. According to this the adsorption appears to be approximately as temporary as the conditions that create it. No? Is it simply the time-factor of the "clean" water diffusing through the live rock that slows it down for people?

However interesting this is, I think I'm very off topic and done hijacking this thread.

Kalkwasser vs 2 part!

Randy Holmes-Farley · Aug 13, 2015

The issue with time of release may be the difference between the simple surfaces of sand grains and the deeper pores in live rock, where phosphate may take substantial time to work its way out.

victornator333 · Aug 28, 2015

Randy Holmes-Farley said:
That isn't true. I show it is stable (if closed and unstirred) in this article. Stirring it can actually degrade it faster, as will leaving it open at the top.

The Degradation of Limewater in Air - Reefkeeping.com
http://reefkeeping.com/issues/2003-05/rhf/feature/index.htm

from it:

Figure 2. The conductivity of the limewater in my dosing reservoir as a function of time.