alk swings in mixed reef

[errand]

My tank is one year old, and has a mix of soft, lps and now sps corals, as well as 3 anemones. Its a 65l all in one, with a skimmer, chiller and I use a seneye monitor.

I do 15l water changes once a week (about 24%) with Red Sea Coral Pro salt and rodi water. My ph has been stable for months, apart from the usual day night trough, at around 8.25. Since I've started the sps I bought a Hanna checker for kH and have been surprised and a bit worried about how much the alkalinity declines over time. For example -

water change on Saturday 4th April, kh 9.2. 

6th April kh 8.8 - I dosed 15cc of bicarb soda in ro water [probably not enough to do much]

7th April kh 8.9

8th April kh 8.3 - I've dosed another 15cc of bicarb soda.

Next water change is due on the 11th, at this rate with no intervention I would have lost 2 kh over the week. And the coral pro salt has quite high levels.

 

The salt seems to be managing the calcium/magnesium really well, as I tested yesterday 490 calcium, and 1610 magnesium [red sea pro test kit]. 

 

Is this a normal kind of weekly depletion of alkalinity?? From my reading this seems like too unstable a swing for sps, am I good to keep microdosing bicarb soda since the calcium/mag levels are fine?

My corals are kind of big apart from the new sps frags, and foolishly i dont have any regular alk tests prior to getting the sps, as I had though the big water changes were good enough and the coral seemed healthy.

 

 

 

[jservedio]

What are you using to check your calcium? If your alk is dropping, your calcium is dropping as well. Just keep monitoring your alkalinity daily at the same sime for a week+ to get a consistent daily usage before you start dosing. You will need to dose both calcium and alkalinity in a balanced fashion (either equal parts 2-part or kalk). Dropping 1/4 of a dKH per day is not out of the ordinary for a tank that's now full of coral and only a year old since you are still likely growing lots of new coralline algae as well.

 

The reason you want to test every day is because while the Hanna is a really good checker, but it can be a little inconsistent if the cuvette glass is slightly dirty, there is a bubble in the reagent, your water has more particulates in it, etc. You need to get a daily trend to figure out what you really need.

[Clown79]

You need to test everyday from waterchange day to the next waterchange day to monitor daily alk use before properly being able to dose.

 

Blindly dosing will create more fluctuations.

 

Often ppl prefer using 2 part dosers to keep ca and alk balanced because they effect eachother. As 1 goes up, the other drops and vice versa. 

 

Most dose according to alk consumption and with 2 part dosers they are dosed equally so that ca isn't effected by alk consumption.

[errand]

thankyou - I have the red sea test kits for calcium, magnesium and alk but also a hanna checker for the alk as well. I've also been polishing the hanna glass with a cloth between every test and sitting it down on the same spot on my desk for testing, at the same time of day [just before lights out at 10pm]. 

I'll start testing every single day then up until next waterchange and then the whole week after that. 

So my tank is finally past the stage where water changes alone will take care of the extra alk/calcium, this is both pleasing and scary, I'll have to go research dosing as much as possible.

 

[this would explain the February tank crash as well since I didn't do a water change for 4 weeks, the alk must have really dived 😞 poor coral]

 

 

[burtbollinger]

that depletion level is about what i experience. i can drop from 9 to @ 7.6 over a week if not doing ESV Bionic 2 part

 

I've learned to let it ride and swing from @ 8 to 9...I dose 2 part every other day or so.  i almost always dose the CA component too, ,but my CA rides so close to 480-500, that i'll skip a dose every few weeks.

 

3 years in after testing daily for 2 years, i now test Alk. via hanna checker once a week and kinda wing it from there...when in doubt, not dosing vs. spiking past 9.

 

 

[Tamberav]

4 hours ago, errand said:

thankyou - I have the red sea test kits for calcium, magnesium and alk but also a hanna checker for the alk as well. I've also been polishing the hanna glass with a cloth between every test and sitting it down on the same spot on my desk for testing, at the same time of day [just before lights out at 10pm]. 

I'll start testing every single day then up until next waterchange and then the whole week after that. 

So my tank is finally past the stage where water changes alone will take care of the extra alk/calcium, this is both pleasing and scary, I'll have to go research dosing as much as possible.

 

[this would explain the February tank crash as well since I didn't do a water change for 4 weeks, the alk must have really dived 😞 poor coral]

 

 

It's not the low alk that is the major issue. Some tanks owners have beautiful SPS tanks that they keep 5-6alk consistently.

 

It is not the number that matters (within reason) but the stability of it.

 

 

[jservedio]

31 minutes ago, Tamberav said:

It's not the low alk that is the major issue. Some tanks owners have beautiful SPS tanks that they keep 5-6alk consistently.

 

It is not the number that matters (within reason) but the stability of it.

 

 

The other cool thing about low alkalinity is that it slows down growth and slows down further depletion of alk/ca. I keep mine down around 6 dkh and even if I miss dosing for a couple days because I forgot to fill the ATO, it never really gets much below 6. I also have a lot of leeway with how much I dose since things start really speeding up if I start creeping up over 7 dkh and it comes right back down. Plus at low alkalinity, things are much more tolerant of swings.

[mcarroll]

You guys are talking about experts keeping expert-level reefs.

 

Keeping alk that low as a beginner who doesn't have the chops to keep a tank stable is asking for trouble.

 

NOBODY should be recommending alk levels that low, IMO, I don't care what they do at home.

[Clown79]

57 minutes ago, mcarroll said:

You guys are talking about experts keeping expert-level reefs.

 

Keeping alk that low as a beginner who doesn't have the chops to keep a tank stable is asking for trouble.

 

NOBODY should be recommending alk levels that low, IMO, I don't care what they do at home.

I think for a beginner it's best to keep alk in normal levels and work on stability.

 

 

[jservedio]

59 minutes ago, mcarroll said:

You guys are talking about experts keeping expert-level reefs.

 

Keeping alk that low as a beginner who doesn't have the chops to keep a tank stable is asking for trouble.

 

NOBODY should be recommending alk levels that low, IMO, I don't care what they do at home.

Fair enough, but I'm curious as to why? Natural sea water is about 7dkh and I stay pretty close to that and found it much easier and far more forgiving at that level to keep it stable.

 

When I first started, I used reef crystals like most new reefers and had nothing but trouble maintaining alkalinity that super-saturated and my corals were far less tolerant of even small swings that high. I highly doubt even now I could manage it. I'm not sure why most salt is over 10 dkh at all.

 

You are probably right that 6-7 is to low for a new reefer, but 7-8 seems like the best bet to me.

[Clown79]

4 minutes ago, jservedio said:

Fair enough, but I'm curious as to why? Natural sea water is about 7dkh and I stay pretty close to that and found it much easier and far more forgiving at that level to keep it stable.

 

When I first started, I used reef crystals like most new reefers and had nothing but trouble maintaining alkalinity that super-saturated and my corals were far less tolerant of even small swings that high.

 

You are probably right that 6-7 is to low for a new reefer, but 7-8 seems like the best bet to me.

I've always preferred alk between 8-9, when I used rscp my alk was too high and ended up with issues. 

 

When I used aquaforest, my alk was 7 but I did notice issues with corals when it dropped too.

 

So for myself I find a good place with alk was moderate levels. Not too low that if it drops it's not  too low but not too high where other issues occurred.

[errand]

So what is the ultimate goal here?? I've been testing every day, it seems to be dropping by .2 dkh every day. Is stable meaning that it doesn't change at all, or doesn't drop more than a certain amount of points every day?? I dont have a dosing pump yet I was going to hand dose. It used to be my weekly water changes were good enough [i do two buckets or 18L at a time, for a 63l tank], and the corals/nems were really growing and happy, then in Feb i got sick with a virus and didn't do water changes for about 4 weeks. I lost 3 corals [gsp, blasto, hammer] and one of my bubbletips started wandering around the tank, so I'm assuming the alk went from about 9 to some horrible level. 

I definitely dont want that to happen again and also I want to get these sps to grow. 

So is stability zero fluctuations or trying to keep levels as close to a range as possible?

[jservedio]

53 minutes ago, errand said:

So what is the ultimate goal here?? I've been testing every day, it seems to be dropping by .2 dkh every day. Is stable meaning that it doesn't change at all, or doesn't drop more than a certain amount of points every day?? I dont have a dosing pump yet I was going to hand dose. It used to be my weekly water changes were good enough [i do two buckets or 18L at a time, for a 63l tank], and the corals/nems were really growing and happy, then in Feb i got sick with a virus and didn't do water changes for about 4 weeks. I lost 3 corals [gsp, blasto, hammer] and one of my bubbletips started wandering around the tank, so I'm assuming the alk went from about 9 to some horrible level. 

I definitely dont want that to happen again and also I want to get these sps to grow. 

So is stability zero fluctuations or trying to keep levels as close to a range as possible?

The goal is to keep fluctuations as small as possible. In your case, you would calculate how much alk supplement to increase your water volume 0.2 dkh and dose that amount daily. You would also dose the same volume of Ca. Keep testing for another week or two since when you do your calculations, your actual water volume is just an estimate. Your 2 part bottles will tell you how many ml you need to dose per gallon to raise alk 1 dkh, so the math is simple.

 

Ideally your alkalinity is exactly the same at the end of the week as it is at that start. As growth increases or decreases, you will have to adjust your dose. If your dose gets big, you'll want to split it up into multiple doses and spread it out over the day.

[mcarroll]

4 hours ago, errand said:

I dont have a dosing pump yet I was going to hand dose.

One of the things with alkalinity is that its level, along with ambient CO2 levels, determines tank pH as well as pH stability.

 

Even at "average" natural seawater levels for alkalinity (7ish) where pH "ought to be" at 8.2....pH in most tanks tends to settle around 7.6 to 7.8.

 

There is a natural day/night pH range that is dictated by co2 consumption and co2 generation from within the tank.  A few tanks seem to land a little higher a few tanks lower...

 

If you take that alk level from 7ish down to 6ish or 5ish as it was in the proposed example I commented on earlier, that potential day/night variation can be really significant....to the point of stressing the animals in the water.

 

Taking you back in time 18 years....this article: Chemistry And The Aquarium: The Relationship Between Alkalinity And pH

...has this chart showing the relationship with alk and pH...

 

If you lower alk to 5ish dKH (1.79 meq/L), all else being equal, pH drops from a hypothetical 8.2 to a hypothetical 8.1.

 

If you're actual tank is starting at pH 7.6 that takes you down to pH 6.6 on average, with day/night swings getting proportionately larger as well.

 

Chemistry and the Aquarium: What is Alkalinity? talks more about the side effects that kick in as pH drops.

 

Low pH: Causes and Cures is another good one to read on the topic.

 

Each one of those articles is a classic now, BTW.  (I wish reefs.com would restore the "browsability" of the old advancedaquarist.com archive that they now own/host....they've destroyed all the internal links for the articles and the table of contents system, such that it was, so finding one article when reading another is very distracting and difficult.)

 

Getting back to alk.  There's a good reason Instant Ocean is built the way it is, with a slightly boosted alk (etc).  That's boosted alk level is what buys someone who manually doses the time they have in between doses to avoid alk levels getting too low (and pH swings getting too large).

 

4 hours ago, errand said:

So is stability zero fluctuations or trying to keep levels as close to a range as possible?

"Stability" as in the stability one would see in the ocean.  The ocean is not unchanging (the opposite), but there are limits on how things change that don't exist in the aquarium.

 

Watch your corals and the tank for signs of change as alkalinity falls post-water change or post-dose.  

 

My corals would show it unmistakably when alk dropped to <=7 dKH...and show signs of stress <=6.  

 

Your mileage may vary on the exactitudes for reasons explained in those articles I linked...but alk and pH do make a difference to the life in the tank.

[mcarroll]

One aspect I glossed over and forget:  

 

Some corals are going to tolerate variances in alk with more or less "aplomb".  That's why I say watch your tank for changes as the alk drops in between doses and water changes.  In general, the less change in between adjustments, the better.   In general, dosing daily is enough for many corals...maybe even most corals.  But know your corals before buying so this isn't a real worry.  I.e. Anything that is known as "sensitive", it's generally for this reason.

[jservedio]

32 minutes ago, mcarroll said:

One of the things with alkalinity is that it's level, along with ambient CO2 levels, determines tank pH as well as pH stability.

 

Even at "average" natural seawater levels for alkalinity (7ish) where pH "ought to be" at 8.2....pH in most tanks tends to settle around 7.6 to 7.8.

 

There is a natural day/night pH range that is dictated by co2 consumption and co2 generation from within the tank.  A few tanks seem to land a little higher a few tanks lower...

 

If you take that alk level from 7ish down to 6ish or 5ish as it was in the proposed example I commented on earlier, that potential day/night variation can be really significant....to the point of stressing the animals in the water.

 

Taking you back in time 18 years....this article: Chemistry And The Aquarium: The Relationship Between Alkalinity And pH

...has this chart showing the relationship with alk and pH...

 

If you lower alk to 5ish dKH (1.79 meq/L), all else being equal, pH drops from a hypothetical 8.2 to a hypothetical 8.1.

 

If you're actual tank is starting at pH 7.6 that takes you down to pH 6.6 on average, with day/night swings getting proportionately larger as well.

 

Chemistry and the Aquarium: What is Alkalinity? talks more about the side effects that kick in as pH drops.

 

Low pH: Causes and Cures is another good one to read on the topic.

 

Each one of those articles is a classic now, BTW.  (I wish reefs.com would restore the "browsability" of the old advancedaquarist.com archive that they now own/host....they've destroyed all the internal links for the articles and the table of contents system, such that it was, so finding one article when reading another is very distracting and difficult.)

 

Getting back to alk.  There's a good reason Instant Ocean is built the way it is, with a slightly boosted alk (etc).  That's boosted alk level is what buys someone who manually doses the time they have in between doses to avoid alk levels getting too low (and pH swings getting too large).

 

"Stability" as in the stability one would see in the ocean.  The ocean is not unchanging (the opposite), but there are limits on how things change that don't exist in the aquarium.

 

Watch your corals and the tank for signs of change as alkalinity falls post-water change or post-dose.  

 

My corals would show it unmistakably when alk dropped to <=7 dKH...and show signs of stress <=6.  

 

Your mileage may vary on the exactitudes for reasons explained in those articles I linked...but alk and pH do make a difference to the life in the tank.

Thanks mcarrol for doing that. It's probably been 6 or 7 years since reading that article and at least a few since reading anything from Dr. Randy. I definitely forgot about the dramatic relationship between pH and alk at lower alk levels and exactly why it works perfectly fine in my tank below 7 dkh: kalk.

 

The low alkalinity in my tank means the "natural" pH is much lower which means I can dose much more kalk before my pH goes off the scale. Because of that, I'm able to run my SPS filled tank off of nothing more than kalk.

 

OP: don't keep your alk below 7 unless you know exactly what you are doing. Or, as in my case, know exactly what you were doing when you made the decision and just forgot why!

 

Sorry we used your thread for this discussion, but I'm petty sure now you know everything there is to know about alkalinity if you read it all!

[errand]

No thankyou all very much thats exactly what I was looking for - reading material and proper advice. thankyou!