Crushed Coral not Raising kH

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TPIRman

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Hi there --

I had a post a few weeks ago in the newbie forum wondering how to raise the kH in my tank (from near-zero/undetectable levels) while avoiding pH bounces, and carpguy suggested adding a bit of crushed coral. So I took a tablespoon of the stuff, put it in the toe of some old pantyhose and made a little baggie out of it. Then I dropped the baggie in the filter and waited. And waited...

I've read all the previous posts on crushed coral, and one of the recurring themes is to be patient, so when I started to get fed up on day 10 with my still-undetectable kH, I told myself to "simmer down now" :p and let things work. But it's been about three weeks now, and it seems that I should have seen some effect.

I'm guessing that the placement or the bag medium (pantyhose, as previously mentioned) might be the problem, but I have no idea. I have a Penguin Bio-Wheel Mini filter, so there isn't much space for "extra" stuff in the first place. Maybe the water isn't flowing well over the baggie. I thought of just putting the crushed coral in the filter box by itself, but most recommendations include some sort of "media bag," so I didn't chance it.

Thinking my kH test might be defective, I squeezed the bag of crushed coral over a test tube and ran the test on the few drops that came out -- the kH read 10, so the test is OK.

I'm getting frustrated -- I think justifiably so this time. The tank is healthy; I'm just trying to safeguard against a pH crash.

Any ideas?

Thanks in advance,
John
 

JSchmidt

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What's your pH?

At this point, I'd double the amount of coral and see what that does. Also, make sure the water is passing thru the bag, and not bypassing it.

Jim
 

TPIRman

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My pH is about 6.8 -- tank details are linked in my sig. One thing I did try is to flatten the baggie out so that it laid along a water surface area, but this just caused the filter to pump a cloud of mulm into the water, as I assume the mechanical aspect of the filtration got clogged.
 

RTR

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A cut section of the leg of the pantyhose would be easier to flow-through. The toes are nomally reinforced and much less permeable. The material should be downstrean of the mechanical filtration.

How large is your tank?
 
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TPIRman

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Good tip re: the pantyhose, RTR. I'll try a section higher up on this now-tattered pair. My tank is 10 gallons -- all the details are linked in my sig, I promise! :)
 

got_nailed

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If you kh is that low and your water source is not going to change I would just put some of the crushed coral in the gravel. Unless your water source changes, you will have this problem for life. I think I would start with ½ a hand full and give it a week and go from there. You will have kh swings every time you change your water. You could pretreat your water in bucket, and hand full of coral and some décor if needed. And give it a set amount of time to sit there (, overnight, 3 days). This would stop the amount of KH swings on your water in the tank.
 

RTR

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The advantage of the coral in a bag is that it can be cleaned or swapped out when it is coated with biofilm. Mixed in the gravel that is difficult or impossible to do, so you have to keep adding. Also in using bags you can adjust the amount used.

Replacement water can be brough up to desired levels with sodium bicarbonate before it is aded to the tank. The reason for not using that as sole control measure is that it is not self-limiting or autmatic. Coral will dissolve as needed once the needed quantity is determined.
 

TPIRman

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OK, so based on everyone's advice, I took a section from higher up on the pantyhose -- definitely a looser mesh, thanks, RTR -- and tried to place it so that it got maximum water flow. Because my filter is so small, it is hard to position the baggie properly without interfering with mechanical filtration or the Bio-Wheel. Here's what I did, though. I folded off one end of the baggie and stapled it, so that there was a broad base. Then I put the crushed coral in and tied off the top. I draped this over the filter cartridge so that it hangs between the cartridge and the Bio-Wheel. (Here's a PDF manual for my filter, a Penguin Bio-Wheel Mini, in case anyone has trouble picturing this.)

As for water changes, there appears to be two schools of thought on this. In my original thread, I raised the water-change concern, and carpguy didn't seem to think there would be a big problem as far as different kH/pH between old and new water. I'm doing 20-25% weekly water changes now that the tank is cycled. Does carpguy's explanation make sense, or do I definitely need to add the proper amount of baking soda to new water once the crushed coral has taken effect?
 

Dapple2

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My water parameters are very similar to yours out of the tap, except my pH is even lower. In addition to the baggie of coral that I can always keep an eye on. I mix some more coral into my gravel and randomly toss a few cleaned shells as well. That seems to keep my levels up at a much more reasonable level and prevents pH crashes. Darn water is so soft it dissolves medium sized shells within a few months. I can watch the progress and see a weekly difference it seems, lol.
 
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