Does water change cause an alk swing ?

tinman

tinman

Well-known member
So I tested my water for alk and cal before the water change

Alk- 6.5
Cal - 380

So I tested my fresh mix saltwater

Alk - 11.5
Cal - 420

And after the water change of about 25-30% my alk is raisin to 8.5

So isn't my water change causing an alk swing ?? Which is bad for sps ??
 
Yes, it is big WC if you change 25-30% with water with high ALK. To do big WC like this get your water parameters as close as possible to your tank water or do smaller changes like 5-10%. ALK change will not be so drastic.
 
Do you dose alk since you have SPS to keep it stable? Seems like your alk drops a good amount between water changes, you will have to dose alk. Alk gets used up faster than calcium


Sent from my iPad using Tapatalk
 
Or possibly do more weekly smaller changes, vs larger water changes. That's what I do to keep more stable parameters.
 
ColaAddict said:
Do you dose alk since you have SPS to keep it stable? Seems like your alk drops a good amount between water changes, you will have to dose alk. Alk gets used up faster than calcium


Sent from my iPad using Tapatalk
Click to expand...

I'll start dosing kalk today with ato water top offs. Trying to figure out how much my tank uses in about 3 days


I'd like my alk to be around 8.5-9.0 but how do I do so with fresh mix having 11 ??
 
Smitty said:
Or possibly do more weekly smaller changes, vs larger water changes. That's what I do to keep more stable parameters.
Click to expand...

You mean like change 2-3 gallons every 2 or 3 days instead of a 6 gallon change once a week ?
 
Try it...I was once doing 5 gals every 4 days, and my tank really responded positively to that schedule. But if you're already doing weekly water changes, then that should suffice, you just have to maybe start dosing a 2 part, because your corals are using the alk and possibly cal quicker than you can replenish it.
 
Tin if u start dosing 2 part u will b fine with around a 5 gallon water change. I do a 5 g wc every 10 days on a 35g system. But I dose reef fusion and keep my leves at
Calcium- 480-485
Alk-9.1
If ur thinking of dosing look into reef fusion. That's what I've been dosing since I started sps.
 
Yep, minimizing the alk spread between your tank water and your fresh will help. I think the kalk will do the trick for you. It's all I use (for now)

I have a lot of sps and I'm able to keep my alk pretty constant around 7.7 -8.0. I do water changes less than once a month and only do about 20%. I do get an alk bump, but it's less than .5 dkh,
 
Sawdonkey said:
Yep, minimizing the alk spread between your tank water and your fresh will help. I think the kalk will do the trick for you. It's all I use (for now)

I have a lot of sps and I'm able to keep my alk pretty constant around 7.7 -8.0. I do water changes less than once a month and only do about 20%. I do get an alk bump, but it's less than .5 dkh,
Click to expand...



Well the problem with longer intervals between water change is I'm not dosing doing anything for nitrates other than relying on water changes ( and now this alk situation comes in to the picture)

And my phosphates are pretty cinstant between 0.02 -0.04 which Should be fine but my nitrates are moving between 0.25 to almost 1.5 after and before the water changes
 
tinman said:
but my nitrates are moving between 0.25 to almost 1.5 after and before the water changes
Click to expand...

I see nothing wrong with nitrates at 1.5. I'm sure you'd be fine as long as they are around 3.0 or so or below.

Yeah, I run biopellets and gfo to allow longer periods between water changes.
 
Sawdonkey said:
I see nothing wrong with nitrates at 1.5. I'm sure you'd be fine as long as they are around 3.0 or so or below.

Yeah, I run biopellets and gfo to allow longer periods between water changes.
Click to expand...

Yea that's what I mean

It's really hard to run those reactors on a biocube. I mean I can run a reactor may be but I should say I'm scared they might do more harm than good before I get it all tuned up.
 
Ok I did only a 2 gallon water change this morning and the alk is now 7

Where do I want it At to be ideal and how fast can I raise it to be there ..

I'm gonna use reef fusion for this one time to raise it to 8.5 and see how much it drops in 3 days and go on from there
 
not in one dose .. i meant like over 24 hours lets say i increase it by 0.2 points every 2-3 hours or so thats more like 10 doses but overall swing of 6.5 to 8.5 in 24 hours .. ??

ill suplement with kalk starting tuesday after the calculations ?


SkullV said:
Don't go from 7-8.5 in one dose.
Click to expand...
 
tinman said:
Yea that's what I mean

It's really hard to run those reactors on a biocube. I mean I can run a reactor may be but I should say I'm scared they might do more harm than good before I get it all tuned up.
Click to expand...

Yeah, I'm not advocating running reactors on smaller tanks. I've got a lot of wiggle room with my tank.

SkullV said:
Don't go from 7-8.5 in one dose.
Click to expand...

I agree that this is a pretty big swing. Maybe you should try dosing some kalk to see what it takes to maintain this alk, rather than change it. The issue is that 7.0 is on the dangerous side of stable. A little drop from there, and you're in the danger zone.

I've been dosing Kalk for nearly a year and I've gotten pretty good at keeping it somewhat stable with only Kalk. If I see that my Kalk is getting high (above 8.0), I'll not add Kalk to my ato for a couple of days. If its where I want it, I'll just add Kalk to keep it stable. If I see alk dropping I'll add vinegar to the Kalk solution to supersaturate it. I test it pretty often and I'm guessing I'm in for a change now that spring has arrived an my evaporation rate will change.

Here is my alk chart. You can see how it went up to 9.0 when I started adding vinegar to my solution. I had to back off the vinegar, and you can see that I backed off too much when it dropped down to 7.0. It's good to know that as my tank starts to demand more, I've got an alk turbocharger.

View attachment 1743
 
Tin man I'm having the same problem. Let me know what u come up with. I lost some Sps do to alk spike when I do WC. Especially with kalk. I was dosing with my ato. Maybe not enought or to much? So keep us updated!
 
i think it kinda makes sense to me now.

here is what i am going to do, and what i have to figure out after talking to you guys and some other fellow reefers.

1. i will slowly increase my alk and calc to 8.5 and 420 over the next 24 hours.

2. Gather times on how much time its taking for me to top off 1 gallon of Ro water via ATO

3. Gather how much alk and cal is dropping over the next days ( so i can understand how much is being consumed on a daily basis)

4. do Math to figure out the amount of kalk that needs to be added to a gallon of RO to maintain alk constantly


and then switch from red sea coral pro salt to red sea salt so my alk level in fresh mix is around 8s instead of 12s.

Phew ..reefing is *************


Thanks Ted, Chad, Gunner and Nino
 
You must log in or register to reply here.
Back
Top