Another alk question

Kershaw · Apr 11, 2016

ok so I have recently my tank is almost a year old and doing mostly great. Coral and fish all look amazing my coral was growing like weeds then one day they just stopped.
Here are peramiters just got done checking them
Kh 6
Cal-450-500
Mag 1350
Phosphate 0
Ph 8
Nitrate <5
Temp 78
Salinity 1.025

Nitrate could be a little higher I checked with elos but I have some trouble seeing the color it isn't 25 it looks like 5 or less
Phosphate was checked with Hanna
Color on coral looks super bright in fact in the 4 years I have been doing this I think my coral has never looked better so I think my issue is alk
Also I have kessil lights that have been on there he whole time. I have also had a problem with ph which has gotten as low as 7.55 so I have been dosing kalk as needed to keep my ph over 7.8

Ok so here is my main question.
Tank is 125 I dose about 2 table spoons of kalk into 1 gallon of water then pour into auto top off. So do I just need to up that amount of kalk I am dosing to bring alk and ph up? And will this cause my cal to go through the roof?
Or is there something I am missing? Thanks for help. Almost forgot, I do have algae but nothing I would consider a problem.

mcarroll · Apr 12, 2016

You need to base your dose on alkalinity test results...or possibly calcium. Not pH. Too many factors figure into pH for it to be used ("chased") this way.

Make sure alk never goes under 7 dKH.

If you are going to dose manually like that, you have to dose every day-pretty much without exception. I did this successfully for years on my tank...but I would recommend a doser that you can more-fully automate.

cjd · Apr 12, 2016

2 table spoons is the most that will dissolve and be usable in a gallon of freshwater. Dosing kalk in ATO is only good to a point in a reef tank, as corals grow they consume more. kalk alone wont be able to keep up. I think you are at a point in your tank that 2 part dosing should be started . As you raise your alkalinity your calcium will lower . Dose small amounts of alkalinity booster daily to bring it towards your goal. Testing both alk and cal. daily . As the numbers move in whatever direction ,adjust dosing till you dose EQUAL parts of cal and alk. It is still fine to use kalkwasser in your ATO as it has many positive benefits then just keeping up with calcium and alkalinity. Just go slow when raising your levels to where you want them....over a couple days . When your levels are where you want them you can determine what your tank consumes at a daily rate and dose equal parts daily . Dose alk first in a high flow area , wait at least 30 min. or so for that to dissipate, then dose cal in a high flow area . You don't want to dose both at the same time, they will precipitate out. I would also just use 1 table spoon of kalkwasser in your ATO as your just wasting most of it and less chance of PH issues if that overflows in the tank. Sorry if I rambled or blew your mind .

Bunnee911 · Apr 12, 2016

Vinegar will allow more lime to saturate. But it is a carbon source and may grow bacteria in your top off jug.

cjd · Apr 12, 2016

what mcarroll said in two sentences , sorry for my paragraph. PH is not the number to chase. tanks will settle in to what they run at . anywhere from 7.8 to 8.4 . All my tanks over the years have run at the lower end of the spectrum with great results . You can run into a lot of problems chasing PH . I would take into consideration what you are using to test for PH (color change method, calibrated PH probe) and even what test kits you are using for everything else. Even the greatest hobby test kits only give us a certain amount of accuracy .

Kershaw · Apr 12, 2016

Understood. I am not as concerned about ph as I am alk. My cal and mag seem fine just my alk is on the low. I guess I will have to start using two part. I thought I would be able to get away with not using it. Because of amount of coral I have and size of tank. But I guess I am to that point.

Rob Lion · Apr 12, 2016

within your reef tank, Ca and Alk need to be balanced, that means for a any given Alkalinity you want to keep to, there is a corresponding value of Ca you must keep to.

450 Ca = 12.6 dKH
440 Ca = 11.2 dKH
430 Ca = 9.8 dKH
425 Ca = 9.1 dKH
420 Ca = 8.4 dKH

2 part dosing makes keeping these in balance much easier, once you have them balanced they should automatically stay balanced if using kalk or the correct proportions of the 2 part you chose to use.

Rob Lion · Apr 12, 2016

Mg is normally preferred as 3 times Ca , so 450 Ca = 1350 Mg etc.

Kershaw · Apr 12, 2016

Ok I'll pick up some two part tomorrow.

Randy Holmes-Farley · Apr 13, 2016

Rob Lion said:
within your reef tank, Ca and Alk need to be balanced, that means for a any given Alkalinity you want to keep to, there is a corresponding value of Ca you must keep to.

450 Ca = 12.6 dKH
440 Ca = 11.2 dKH
430 Ca = 9.8 dKH
425 Ca = 9.1 dKH
420 Ca = 8.4 dKH

2 part dosing makes keeping these in balance much easier, once you have them balanced they should automatically stay balanced if using kalk or the correct proportions of the 2 part you chose to use.

IMO, the optimal calcium level is not tied to the actual alkalinity level.

Rob Lion · Apr 13, 2016

If the optimal calcium level is not tied to the actual alkalinity level, what is it tied?

Randy Holmes-Farley · Apr 13, 2016

Coral biology. IMO, the optimal calcium level is about 400-450 ppm regardless of anything else.

The only apparent drawback to higher levels is increased precipitation of calcium carbonate, bit 450-550 ppm calcium is certainly fine.

The drawback to calcium below 400 ppm is that it can become limiting to coral growth, and the lower it is, eth more limiting it becomes.

Kershaw · Apr 13, 2016

So if I understand. If I use kalk to raise alk it is going to cause my calcium to go way up? So I need a two part to get them inline then try and use kalk to maintain?

Randy Holmes-Farley · Apr 13, 2016

Kershaw said:
So if I understand. If I use kalk to raise alk it is going to cause my calcium to go way up? So I need a two part to get them inline then try and use kalk to maintain?

No, that isn't true. Limewater raises calcium by 20 ppm for each 1 meq/l (2.8 dKH) of alkalinity.

So calcium never gets too high from any reasonable alk boost.

Limewater does very, very slowly raise calcium relative to alk because even though it provides the same ratio of calcium to alk as in calcium carbonate, but in seawater, magnesium gets into the crystal in place of some of the calcium.

What you cannot do is boost calcium substantially because alk will rise too much.

Kershaw · Apr 13, 2016

Ok. Thank you all. But now I still am not sure what to do. Should I use two part or kalk to get my alk up. I had explosive growth on coral around 9. So that's where I am shooting for

cjd · Apr 13, 2016

Personally I would use two part to get the levels up since you are going to have to dose anyway . I use EVS B-Ionic 2 part . Many other commercial brands and even home recipe's that are just as good.