Snail relationship with "stable" KH? - The Planted Tank Forum
 
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post #1 of 11 (permalink) Old 12-26-2004, 09:53 PM Thread Starter
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Snail relationship with "stable" KH?

To all viewing this post, I hope you are had a lovely holiday! And apologies for the long post. For the benefit of the reader, I'll leave the details behind my question to the last.


BRIEF BACKGROUND
My KH is typically unstable because I foolishly placed a thin layer of crushed coral under my substrate. Also, I recently discovered snails in my tank. And all of a sudden, my KH has become stable, no longer changing significanly over time.


QUESTION
Is my KH more stable now because calcium in the water, being liberated from the coral under the substrate, is being absorbed by the snails for shell growth, instead of driving up my KH? Could these two events below be related?


========= long winded details below ====================

EVENT ONE DETAILS - Stable KH
When I set up this, my first, planted tank, I was concerned over the very low KH that our tap water has here, and the potential instability it might foster in my tank. My tap KH is around 1.75. Wanting to raise it a bit, and thinking myself clever, I foolishly put a thin layer of crushed coral down first, before laying down my primary substrate. I tested a large quantity of this stuff in the tank first, and only saw minor movement in KH. Problem was of course, I only tested one day. So now, for the last nine months I have been forced into weekly water changes, like it or not. A normal 50% water change, using tap water, will yield a tank somewhere between 3 and 4 degrees KH. But within a week (every week) that creeps up to almost 6. Short of constantly tinkering with pH set points on my SMS controller, I'm forced into a large water change, lest my CO2 PPM go thru the roof and kill my fish, not to mention the impact a climbing KH might have on the plants. So instead, with the water changes, they get the weekly see-saw. Until lately...

A few weeks ago I got some plants from one of our sponsors, and loaded my tank up with new plants. An unfortunate run-in with a large predatory crustacean (different post) caused major tank upheaval, and much replacement of plants. The substrate and coral were fairly untouched - or at least no more than you would expect from any major replanting. But since about a week after that planting, my KH has stopped moving, or at least nowhere nearly as much. For months it moved almost 3 degrees a week. Now it moves no more than half a degree. I find myself in the unprecedented position of possibly having to raise the KH in my tank. A dramatic change.


EVENT TWO DETAILS - Snails
Since I started this tank, I have vigorously avoided snails, inspecting and treating every plant before it went in. Many plants dipped in treatments, many snail egg covered leaves removed prior to using plants. In fact, I've generally quarantined plants for 10 days. That is, until the aforementioned large infusion of plants. They would not fit in my quarantine tank. I was so overwhelmed with the volume that I omitted my normal anti-snail dipping, and opted for a visual inspection alone. One week later, I saw my first snail in the tank. A very small MTS. And this last week, upon my first major trim from the replant (I waited a few weeks to allow them to settle) I found a reasonable number of tiny snails of some different variety - 8 or 10. Now I have snails, I assume from the last planting, since I've never seen them before.


Are these two seeminly independent events related?

Steve - 33g reef and a 180g planted in need of a re-scape.

Last edited by scolley; 12-27-2004 at 02:01 PM.
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post #2 of 11 (permalink) Old 12-28-2004, 09:01 PM
 
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Part of the fun with this hobby is stuff just like this. Probably futile, but what the heck, let's speculate.

Are you thinking of earthworms and the garden? If you killed all the earthworms, your garden wouldn't do as well. Hmmmm... snails are like earthworms in some ways...

God's grand design, each organism in the fragile ecosystem in a delicate and complex relationship with each other. Hmmm... snails stabilizing KH? Why not?

I would like to see someone with a chemistry background (as opposed to an old windbag like me) take this one on. What is KH? is it concentration of CO3-ions in solution? What can buffer the buffer? Anyone???
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post #3 of 11 (permalink) Old 12-28-2004, 09:11 PM
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Lets look at the facts...

1.) You've had a thin layer of crushed coral in your substrate for 9+ months
2.) You've recently added a number of new plants
3.) You have a few tiny snails

Theory #1:
The Crushed Coral is starting to break down and is releasing less Calcium into the water

Theory #2:
You have some Calcium hungry plants that are stripping it out of the water/substrate

Theory #3:
Combination of the two above points

Theory #4:
Your killer crustacean has returned from the bowl to haunt your tank. We all told you he'd come back didn't we?


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post #4 of 11 (permalink) Old 12-29-2004, 01:42 AM Thread Starter
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Quote:
Originally Posted by ksand
God's grand design, each organism in the fragile ecosystem in a delicate and complex relationship with each other. Hmmm... snails stabilizing KH? Why not?
I'm not really suggesting that snails stabilize KH, per se, like earthworms in a garden. In fact, were I suggesting anything, it would be that snails DE-stabilize KH, driving it down as they take up minerals. In my particular case, where the KH trends upward, that could have "stabilizing" effect. But for someone with snails but nothing to drive up their KH, is would drive it down, or maybe lead to calcium deficiency in their plants.

I don't know. I'm still too new here...


Quote:
Originally Posted by GDominy
Theory #1:
The Crushed Coral is starting to break down and is releasing less Calcium into the water
"Starting"? It's been very, very predictable for the last nine months. Why the changes all of a sudden like this? I don't know...


Quote:
Originally Posted by GDominy
Theory #2:
You have some Calcium hungry plants that are stripping it out of the water/substrate
Hadn't thought of that!


Quote:
Originally Posted by GDominy
Theory #3:
Combination of the two above points
right


Quote:
Originally Posted by GDominy
Theory #4:
Your killer crustacean has returned from the bowl to haunt your tank. We all told you he'd come back didn't we?
I consider this to be a question of my own personal karma. Whether or not the crustacean comes back has nothing to do with what you guys predicted. I believe it is only governed by how many nickels I've got in my good-karma bank. Which, of course, is why I give the bowl a good little look around each time I take a bio-break.


Thanks for the input folks. I'm stumped on this one. Maybe it's the plants - but thats a lot of calcium!

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #5 of 11 (permalink) Old 12-29-2004, 02:28 PM
 
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Don't give up!

For 9 months, the KH would rise between 2 and 3 degrees KH. So if...

1 °KH = 17.875 ppm CaCO3

a rise of 3 °KH means the crushed coral was putting...

3 x 17.875 ppm = 53.55 ppm

...into your water. Now, isn't ppm the same as mg/l? You didn't tell us your tank's size. You could calculate how many grams of CaCO3 were being dissolved into your water from the crushed coral.

That would give you an idea of the quantity of CaCO3 involved.

Have you been measuring GH all this time? That might give us a clue.
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post #6 of 11 (permalink) Old 12-29-2004, 05:18 PM Thread Starter
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Thanks ksand. I wasn't trying to be cryptic or evasive... I just don't know enough to know what information might be relevent to the question. But here goes...

1) The tank is a 20g, but I figure nominal water volume to be around 16.75.
2) Please keep in mind, that 2.5 to 3 degree rise was each week, not over the 9 months of the tank.
3) GH - I only recently got a reasonably reliable GH kit. And right now it measures 8 degrees. But my historical information unfortunalely come from one of those multipurpose dip strips, which when I read it, is about as reliable as flipping a coin. Those tests have consistenly yielded 6 to 10 degrees GH, but typically I read it as 8.

So...
16.75g x 3.785g/L = 63.4L

at 53.55mg/l CaCO3 (thanks!) thats 3395mg CaCO3, or 3.3g

And that's PER WEEK

3.3g CaCO3/week x 37weeks (I checked), is 122g CaCO3 or 4.3 oz.


But if we are going to consider that the CaCO3 is all gone from the crushed coral now, there are a few things I don't know...

1) What %, by weight, of coral (w/small white shells mixed in it) is CaCO3?
2) And what weight did I put in my tank?

I think I put in several cups. I still have the coral, but no way to weigh it.

But it's possible that the CaCO3 is being used up by the sound of things. What do you think?

PS - I did a 40% water change to exactly 5 days ago, which brough my KH down to 3 degrees. I didn't change more water as I did not want the KH to go below three. As of today, it measures 4 degrees. So, it's not moving as fast as it used to, but it is still moving.

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #7 of 11 (permalink) Old 12-29-2004, 07:07 PM
 
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Quote:
Originally Posted by scolley
... I wasn't trying to be cryptic or evasive... I just don't know enough to know what information might be relevent to the question.
Yup. Understand. Didn't think you were.
Quote:
Originally Posted by scolley
3395mg CaCO3, or 3.3g

And that's PER WEEK
I see you picked up the ball and carried it further, now we have some numbers to work with. I guess a gram is a tiny amount, so it's plausible that 3 grams of limestone per week were dissolving into your water for those 9 months.

Quote:
Originally Posted by scolley
...Those tests have consistenly yielded 6 to 10 degrees GH, but typically I read it as 8....
Could you measure GH out of the tap? With a KH of 1.75, if your GH is 8, aren't Mg, etc really high? Maybe your tap water changed.

Quote:
Originally Posted by scolley
...What %, by weight, of coral (w/small white shells mixed in it) is CaCO3?...
Yup. The question to ask at this point. The only way to find out is weigh some, leech out all the limestone, then weigh it again, or maybe google will bring me some grad student's thesis :-)...

Quote:
Originally Posted by scolley
... And what weight did I put in my tank?...
A good guess is better than nothing :-)

Quote:
Originally Posted by scolley
...But it's possible that the CaCO3 is being used up by the sound of things. What do you think?
Yup. Water changes. Plant uptake. I would say snails need Calcium, just like people, and probably get it from the stuff they eat.

Quote:
Originally Posted by scolley
PS - I did a 40% water change to exactly 5 days ago, which brough my KH down to 3 degrees. I didn't change more water as I did not want the KH to go below three. As of today, it measures 4 degrees. So, it's not moving as fast as it used to, but it is still moving.
OK, so there's still limestone dissolving, but at about 1/3 the rate as before?

Last edited by ksand; 12-29-2004 at 07:08 PM. Reason: Correction
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post #8 of 11 (permalink) Old 12-29-2004, 09:51 PM Thread Starter
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Thanks ksand. Man, you're a trooper on this one!

I don't know the Mg in my water, but the K is .9 ppm, if that is an indicator. The last thing my plants need after a water change is more Potassium.

I poured over my records this afternoon, and found to my surprise that early on in the life of the tank (and my relevant knowledge), that for the first six weeks or so the movement of KH was less than 1 degree a week. But before a few months went by, it was up to about 2.5K a week. Sorry, I was wrong about the 3. And there were occasion spikes - I'll assume due to replanting and/or disturbing the substrate.

Now I'm at 1.4 a week. this week anyway. or about 60% of my old rate. It seems like I'm quibbling here, but...

1) The change in rate came on quickly, and I thought the snail question was an interesting possibility. Oh yeah, it's got to be more than a few. The 8 or 10 I found were in a single golf ball sized hunk of floating riccia. Who knows what's in the tank.

2) It's a problem because if the rate does not increase, and my tap stays at 1.75 K (est.) I can't do a 50% water change each week without lowering my average KH over time. Additives are an alternative, but I'd rather avoid that if I can - Rex's "chasing the dragon" but with KH instead of pH.

So I suppose I watch an wait, change a bit less water as I consider baking soda. And I hope some graduate student can answer the original question.

But I'll assume it's not the snail, for if it were, having snails would reek havoc on your average "stable" KH tanks.

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #9 of 11 (permalink) Old 12-30-2004, 01:47 PM
 
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No problem, man, I like to learn new things. Each new phenomenon we observe in our tanks is a puzzle to be solved. The questions are more interesting than the answers.
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post #10 of 11 (permalink) Old 01-01-2005, 12:03 AM Thread Starter
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Thanks ksand. If anything changes, to provide a bit more insight into this academic (but fun ) quesition, I'll post it. Cheers!

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #11 of 11 (permalink) Old 12-16-2006, 05:07 AM Thread Starter
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Question re worded - thread ressurected

I asked the wrong question when I started this thread a few years ago. Sorry, I didn't know any better. The question should have been...
Can snails cause a measurably downward affect on your KH?
My first experience with the issue, as posted previously, would indicate "Yes, they can." I'm posting now because I've got further evidence, that while not well documented enough to be iron-clad proof, is enough to convince me that my conclusion is correct.

I've got a tank that I've been doing frequent water changes in. I use tap water for the changes, and that tap has a KH of about 1.75 degrees. I use a Lamotte test kit, so if it is not a accurate reading, it is certainly precise.

My KH has been very stable until I had a snail outbreak, caused by the death of my snail eating loaches (caused by my medicating my discus). Though my KH had been reading rock solid since the start of my tank several months prior, within 30 days of my snail population increase, my KH dropped to 1.3 or 1.4.

I purchased a replacement loach, and it immediately began to pound the snail population. I was able to cease my daily task or pulling snails out of the tank. The population reduction was immediately evident (a plug for zebra loaches IMO!). But more importantly, my KH rose to 1.6. And now, a few weeks later, with practically no snails to be seen, it's back to 1.75.

This is not well documented science, I know. But I know the diligence with which I record my observations of my tanks. And I know the precision of my test kit. And my conclusion is one I'm personally certain of:

Snails can lower your KH.

I hope that helps our community understanding.

Steve - 33g reef and a 180g planted in need of a re-scape.
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