what makes KH drop quickly?

[Skeptic9962]

tested my KH on sat. and it was at 9.5 and tested yesterday and droped down to 7.5.....what would cause this drastic of a drop? other params are:

salinity 1.025
ph 8.2
alk 8 (today)
calc. 425
mag. 1100
nitrate 0

dose kalk in my top off to keep levels maintained...after this drop in KH ive noticed a few of my sps are STNing..could that be the cause of STN also?

thanks for any input

 

[trido]

It could be that your Mg levels are low. Try to get them up and keep them closer to 1350 as a target. This should help keep you alk/Ca levels balanced like they were 9.5dkh/425
Yes, a sudden drop in alk will cause STN

 

[returnofsid]

Extremely high or low Alk will cause STN. I've experienced both. The worst was when I overdosed Alk and had more of an RTN episode, that some of my corals never recovered from.

I'd also bump up your Mg to a level 3X your Calcium level. Magnesium plays an important role in keeping Alk and Ca balanced. Also, what type of substrate do you have? Aragonite based sand acts as a buffer for your pH and your Alk, but with your pH at 8.2, i don't see that coming into play.

 

[as1720]

What's STN/RTN?

 

[returnofsid]

Slow Tissue Necrosis/Rapid Tissue Necrosis

 

[vwmoneypit]

yep just went through that ..Dont take much off the scale b4 u see a change and do something.I lost half my hammer! .How old is the tank ?

 

[Skeptic9962]

well i tested everything on saturday...and thought mag. was low so added some sechem mag. buffer what was recomended was 25g at most. and every 5g would raise it by 5 so i did the max of 25g so it would raise it 25points figured idd do that for the next couple days...then tested it 2 days later and had droped my alk....did i overdose? and what would be the easiest/best way to get the mag back in line cause i tested it again today mag was still sitting at 1100 or so before my water change did a large water change tonight hopeing for it to level it out possibly a bit.

 

[Skeptic9962]

my substrate is about 1.5" of live araganite..

Extremely high or low Alk will cause STN. I've experienced both. The worst was when I overdosed Alk and had more of an RTN episode, that some of my corals never recovered from.

I'd also bump up your Mg to a level 3X your Calcium level. Magnesium plays an important role in keeping Alk and Ca balanced. Also, what type of substrate do you have? Aragonite based sand acts as a buffer for your pH and your Alk, but with your pH at 8.2, i don't see that coming into play.

 

[Skeptic9962]

i combined both of my tanks into a new 75g about 2 months ago or so replaced all water/sand but all the live rock was from the other 2 tanks...whats wierd is everything looked amazing just untill a few days ago...trying to think of anything else i did diferently lol...only other thing i can think of would be the fact that i dose kalk mix it up in a 10gal tank then let it settle and have a mj400 with jbj ato dose it as the top off and the other day the pump droped to the bottom and im guessing was sucking up some of the sediment on the bottom....

yep just went through that ..Dont take much off the scale b4 u see a change and do something.I lost half my hammer! .How old is the tank ?

 

[roscoe]

IMO when everything else fails. Water changes is the best equalizer. JMO though.

 

[Skeptic9962]

ya i just did a 15gal. change last night and was planning on doing a 10gal. tomorrow afternoon. hope that will kinda take care of whatever it is...cause only a few are STNing

IMO when everything else fails. Water changes is the best equalizer. JMO though.

 

[Boomer]

It is not that low Mg++ drops the Alk, it is that low Mg++ increases the precip of calcium carbonate which then pulls down your dKH and Ca++. So, if that is the issuee you are actually using or adding more Ca++ than needed due to low Mg++. But if your Ca++ is not dropping also quiclkly then it is not the Mg++. Alk can also drop quickly from high bioloads, which is often the case.

As far as the buffer effect of Aragonit sand is is nil and has no impact and the amount it adds can not even be meaured it is so low.This buufer effect of carbonate sands and gravels is a myth that just does not want to fo away