Alk/Calc Precipatation HELP

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SteveL99

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@Randy Holmes-Farley

I've read quite a few threads about this topic and many of Randy's articles on reefkeeping.com and other places online. I fee like I've got a pretty good handle on this, but my levels just aren't making sense. I would really appreciate any advice you can give (and thank you for your time).

New tank started 10/10/2020. Started with "real reef" rock (supposedly pre-cycled) and then added 4 bags of live sand (Caribsea). Cycle completed 11/15/2020. I wanted to get my levels up and steady before adding fish, so I started dosing two-part from ESV. Doing so, I got my Alk to around 8.5 and pretty stable, but my calcium started dropping. I started adding calcium in much higher ratio then my Alk to balance. Keep in mind, there are no corals at all in this tank. I then added two tangs to help get me through the ugly stage. After several weeks, I finally started to see some diatomatious algae (brown), so I used my rake so mix up the sand. I found the entire sandbed was covered in rock-hard sand clumping. I researched your articles and realized by aggressively dosing two-part with no corals (little or no take-up), I believe I created the clumping since the super-saturated solution had nowhere to go but into solid form. (I THINK this is correct, but for reference my levels were CA = 440 and Alk = 8.5). After reading your posts about sand clumping, I turned off the two part and planned to turn it back on after corals are introduced in a few months.

But now my levels are plummeting. My Alk is now about 6.5 and my Calcium is below 300. I'm lost. Do I turn the dosing back on at a much slower rate? Water changes? I know fish aren't as sensitive, but i want fairly stable levels that are in-range. Again, any advice would be greatly appreciated!

Other parameters:
Salt = 1.026
Nitrate = 1.0ppm
Phosphate = 0.02
 
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Randy Holmes-Farley

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In this situation, I'd avoid dosing alk for a substantial period, then when you restart, use sodium bicarbonate for alkalinity to help bring the pH lower and keep the alk no higher than 7 dKH. Don't use other pH raising means, like a CO2 scrubber.

I'm surprised the calcium is able to get that low. Try the kit on some new salt water. If it really is that low, I'd boost it to 420 ppm with calcium chloride.
 

blasterman

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I would also get a second opinion / test on your calcium. Lots of things will deplete alk in new tanks at astonishing rates even though you don't have coral. However, calcium isn't going to just vanish unless you are precipitating it. That's why I harp on beginners to stop linking calcium and and alk together.

Alk levels below triple digits won't precipitate calcium and you have to drive Calcium levels up to well over 500 before magnesium says 'oh hell, I give up' and it starts precipitating. That leaves your test kits.

If it's a fish only tank I'm not sure why you are dosing or bothering with calcium at all. It's like doing oil changes on a car you park in your driveway for 6months at a time. I would put the calcium test kit away, do a water change, and just test for alk once a week. Keeping alk elevated in a new tank does help new tanks get through uglies because it's consumed so fast by establishing tank biology. Calcium isn't.
 
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SteveL99

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I would also get a second opinion / test on your calcium. Lots of things will deplete alk in new tanks at astonishing rates even though you don't have coral. However, calcium isn't going to just vanish unless you are precipitating it. That's why I harp on beginners to stop linking calcium and and alk together.

Alk levels below triple digits won't precipitate calcium and you have to drive Calcium levels up to well over 500 before magnesium says 'oh hell, I give up' and it starts precipitating. That leaves your test kits.

If it's a fish only tank I'm not sure why you are dosing or bothering with calcium at all. It's like doing oil changes on a car you park in your driveway for 6months at a time. I would put the calcium test kit away, do a water change, and just test for alk once a week. Keeping alk elevated in a new tank does help new tanks get through uglies because it's consumed so fast by establishing tank biology. Calcium isn't.

In this situation, I'd avoid dosing alk for a substantial period, then when you restart, use sodium bicarbonate for alkalinity to help bring the pH lower and keep the alk no higher than 7 dKH. Don't use other pH raising means, like a CO2 scrubber.

I'm surprised the calcium is able to get that low. Try the kit on some new salt water. If it really is that low, I'd boost it to 420 ppm with calcium chloride.
My test results were from my Neptune Trident. To compare, I tried two more test kits today. One red 290 and the other was somewhere around 300. So I believe my Trident is fairly accurate in this case. My magnesium is just below 500.

Its not a fish-only system, but I don't plan to add corals for another 6 months or so until all fish are in and I'm confident I don't have significant algae problems. I plan to boost Calcium w/ Calcium Chloride and will stop dosing Alk for a while.

I appreciate both your advice.
 

Randy Holmes-Farley

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My test results were from my Neptune Trident. To compare, I tried two more test kits today. One red 290 and the other was somewhere around 300. So I believe my Trident is fairly accurate in this case. My magnesium is just below 500.

Its not a fish-only system, but I don't plan to add corals for another 6 months or so until all fish are in and I'm confident I don't have significant algae problems. I plan to boost Calcium w/ Calcium Chloride and will stop dosing Alk for a while.

I appreciate both your advice.

The magnesium is not 500 ppm. Is that a typo? 1500? If not, you are probably reading the syringe backwards.
 
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