Looking for some insight on my ALK issue

[MJAnderson]

I'm baffled by this and the chemistry forum just seems to say "measuring error" so I thought I would try here.

For 4 months I've been topping off with kalk. On my 72, I use 1.5 tsp of kalk per gallon of RO, so it's not fully saturated. I top off about 1.5g per day. I can't seem to keep ALK up and Calcium steady. If I increase to 2tsp, my calcium creeps up but my Alk stays around 8.5-9.5. Where I am now, my calcium stays steady but my ALK range drops about 0.25 per day. My Mag stays in the low 1300s. When I asked in the chem forums, Randy said to keep ALK steady as there is more issues with testing errors with calcium. But over a few weeks my calcium creeps up. When it hits 1500, I top off with just RO and use baking soda daily to keep the ALK steady until it hits about 1400 then start back up with the kalk topoff.

Any thoughts? Is there another piece of this equation Im not measuring? PH stays at 8.1-8.5 and I have a PH meter, recently calibrated. SG = 1.026 and temp is set from 79.8-80.2.

 

[Kreeger1]

Do you mean calcium hits 500?
Thats a hard one to figure out how stable does your ph stay?

 

[serpentman]

I am having similar issues as well which I suspect is due to a Mg inbalance.

In your case, as long as your Ca levels are relatively high and the pH stabilizes, I wouldn't be overly concerned. If I am not mistaken, raising your alk too high will result in more calcium precipitating out of the water. I would be more concerned with the larger swings in pH.

 

[MJAnderson]

Sorry, calc hits 500, not 1500.

When I keep my ALK around 9 +/- 0.5, my PH ranges from 8.1-8.5. As ALK drops, my PH swings from 7.7-8.3, so lower numbers and larger swing. I have an ACjr, so I get hourly PH readings.

I think I might have the answer. I do 10% weekly water changes. Someone asked if I used Tropic Marin Pro, which I do. Seems it mixes low in ALK and high in calcium. Guess I should buffer my mixed salt water to normal levels and adjust my kalk concentration. I never thought to test my mixed water.

 

[lawdog]

I use Tropic Marin Pro as well I never have a problem with my levels although I run a Calcium Reactor on my setup so everything stays put. Have you tried 1.75 tsp's to see if that is the magic amount. It is really hard to keep everything level when you are dosing things adding baking soda, adding kalk, etc...

Maybe a calcium or a kalk reactor might help you keep your levels more stable. ... just an idea.

 

[MJAnderson]

Craig,

I was checking out the chem forums and a few people have measured low ALK with TMP. The typical solution seems to be a 60/40 mix with IO, which is low in calcium but high in ALK. The seem to cancel each other out.

Wish I could fit a calcium reactor under my stand. But a new tank is being planned and it will have room. =)

 

[lawdog]

Have you tested your TMP? After reading this last night I went and did a small batch and tested the CA and the ALK. CA came out at 450 in the batch and ALK tested out at 8.5. Still within acceptable ranges but a little lower than I usually like to keep mine as NSW usually tests out around 8.0, but I get better growth keeping ALK around 9-9.5.

Not sure how low others are reading but it doesn't really affect my tank at all and I have always had much better results using TM or TMP than any other salt out there.

I am not a chemist and would not ever think about trying to do a 60/40 mix with another salt to try and get levels matched up... Most people say that when you buy a bucket of salt no matter what brand unless you plan on mixing the whole batch at one time you may get a different mix. Ex. You buy a 200 gallon bucket of TMP but you only mix up 20 gallons at a time, the whole batch of 200 gallons would mix up perfect but depending on the actual mix of the batch scooping out 10% of the bucket and mixing it up may alter the levels a bit. The salt is made to be mixed up all at once... Maybe I should start buying the smaller boxes and using it all at once... don't know. But for the price it doesn't make sense.

If I test lower than I want it I usually just add a little baking soda to bump it up and then my Calcium reactor keeps things stable.

You can always run a calcium reactor next to your stand like I used to do and hide it in a matched cabinet. Just run the effluent line into your sump behind the stand. Reactors are truly the next best investment in this hobby behind Skimmer and Lights... water quality is key and keeping params stable is key so it just makes sense.

 

[MJAnderson]

It might be my batch? I wonder if it goes bad. I'm at the bottom of the bucket and it's 4 months old. Mine tested around 7.5 with CA also at 450. changing 10% of my water weekly with ALK 2 points below what I wanted it seems to be the cause. I'll see what a new bucket gets me, although after reading the MACNA posts about Red Sea being better I might switch with this bucket. I know Aquatic Technology in Columbia Station carries it.