does crushed coral lose its "potency"?

[crazycat]

my tap water has a kh of about 2dkh. when i initially set up my tank, i filled one of my filter baskets with cc and raised the dkh to 10. i then kept my ph at 6.9/7.0 where i was getting about 30ppm of co2.

after cleaning both my filters, and after an outbreak of bga (which is gone thankfully, treated with erythromycin), i have noticed that my kh has fallen to about 5.5 dkh. i just added more cc to the filter assuming that perhaps the cc is "worn out". is this a correct assumption?

my water chemistry is all out of whack. i have 20ppm nitrates. 4ppm phosphates!!! (too high!) and now at 7.0 ph, only about 19ppm co2. i'm not really sure why the po4 is so high--and i'm not really sure what to do about it. my thinking is if i raise the amount of co2, it will help the plants uptake no3 which will ultimately reduce the po4. is this correct or i have i got things confused?

any other ideas on how to get my levels back to normal?

will the learning curve ever end?

 

[rich311k]

Yes CC does need to be replace periodically. It last 4-6 months if I remember corrrectly.

 

[sherry]

Is it possible that bioload feeding can hit a point where plant uptake can't bring po4 down enough.. and wouild twice weekly water changes for a while help?

I'm asking because I think I'm heading in the same direction and would really like to know..

could the answer be more co2 plus more water changes?

 

[BrianNY]

Well, you can never be too thin, too rich, or change too much water. LOL

cc will lose it's capacity to add carbonate hardness eventually. I replace mine probably more often than I should and that's about every 4 months. I don't think the CO2 will have any effect on PO4. I have used phosguard in my filters to get high PO4 down.

HTH

 

[Purrbox]

The Crushed Coral will slowly completely dissolve into the water column. If you happen to have a couple of larger pieces, it's very easy to see the difference in the size after a few months. So like anything else, you need to add more periodically to replace what has dissolved and then be removed through water changes.

 

[Simpte]

Why are you adding crushed coral to a planted tank? If you want to raise KH baking soda is easier as you can adjust it to exactly what you want and its cheaper.

 

[crazycat]

it's my understanding that crushed coral creates a more stable kh. and one less thing to have to monitor and dose. i also have a 15lb bag of the stuff which is going to last me for at least another 2 years

 

[malkore]

Why are you adding crushed coral to a planted tank? If you want to raise KH baking soda is easier as you can adjust it to exactly what you want and its cheaper.

Its really a matter of preference. Some places CC can be bought so cheaply, and its such a low-maintenance way to raise Kh, that its attractive to some people.
Others prefer a more controlled way of raising Kh, and will use baking soda in measured amounts after every water change. These people also tend to have really soft, acidic water to begin with, or are trying to hit specific levels for a reason, such as inducing breeding cycles.

more control, a little more work.
less precise results, but you only bother with it 3-4 times a year.

Both are fine.

 

[crazycat]

thanks malkore!

any ideas on what to do about my phosphate? and why it's so high?

 

[greenmaji]

CC when exausted has been known to start leaching some PO4.. see if the old CC wasnt the culprit..

 

[crazycat]

i didn't actually get rid of the old stuff--i just added more. but i can certainly remove the old cc. in the meantime, do you have any suggestings on how to lower the po4? isn't 4ppm pretty high--like bad high?

 

[greenmaji]

yes.. long term 4ppm is too high IMO..
recomended NO3:PO4 is 10:1

if you remove the sorce then the equivelent of a 75% water change should fix the PO4 level.. roughly..

btw.. if anyone was wondering were I read that depleted CC leached PO4 it was from reading about calcium reactor media that SW hobbiest use and why they were avoiding CC..

 

[crazycat]

thanks gm!

 

[greenmaji]

ahh.. no problem..

 

[malkore]

4ppm is 'bad high' only in that it could spawn nasty algae. it won't harm your fish though.

(just wanted that clarified)