Low alkalinity

[ants86]

I've been experiencing some issues with my alkalinity being consistently low. I have a 60 gallon mixed reef, with about 10-15 different types of softies and mushrooms, about 4 acans, 1 large hammer, 1 open brain, and only 2 SPS (red cap and stylophora). I don't think my system demands high calcium or alkalinity, but I could be wrong. I also use IO's Reef Crytals.

My alkalinity has been running around 6 dkh usually just one week after a water change (I do bi-weekly 20-25% water changes), but calcium levels stay around 420-450 and magnesium around 1400. Other parameters are:

Ammonia: 0
Nitrites: 0
Nitrates: 5-10 (I know that's a little high)
Phosphates: 0

My acans used to do really well, but since changing from T-5s to LEDs about 2 months ago, 3 out of 4 of them have not been opening fully. I can still see the flesh and they still have a feeding reaction, although the reaction is much weaker. All other corals are doing fine, except for the ever-temperamental toadstool mushroom.

I tried dosing baking soda, which brings up the alkalinity temporarily, but even after a water change it usually drops back to about 6 dkh. Does anyone have any theories as to what's going on? Do you think the acans not opening have anything to do with the low alk? Thanks!

 

[Animal-Chin]

When I mix my instant ocean salt with my RO water the alk is 6. Seems to be how it mixes. You can get all sorts of additives for alk, I use soda ash but there are tones of 2 parts on the market.

Acans seem to like lower light, maybe your LED's are just too bright? Can you dim them a little?

 

[ants86]

Yes, I can dim my lights, but the max I'm running my razors is 75% on both channels for around 6 hours a day. My acans are in the bottom third of the tank. It's a 2 ft tank but the lights are mounted low, around 4 inches off the top of the tank. One of my acans does look like it bleached though, since the flesh used to be a dark green and purple but the flesh towards the top seems almost translucent now. The others don't look like they're bleached but are just not opening fully.

The weird thing is that 1 out of the 4 acans is doing perfectly fine, although it's predominantly white with some pink. Would the darkness or lightness of a coral's color determine how easily it can bleach? That theory makes some sense to me since presumably a lighter coral would have less zooxanthellae to begin with? Or I could be completely off-base lol.

 

[mr_X]

Acans do best in low light situations IME, and LEDs can be quite deceiving. I have a stylo on the sand bed and it's doing fine. different colored corals can react differently, as well as like corals collected from different areas. Even the light that was over the tank you bought them from makes a difference.
As far as the alk, what is it just after the water change?

 

[ants86]

As far as the alk, what is it just after the water change?

I'm doing a water change this weekend, I'll test it and report back. I should also test the alk of the water I'm using for the water changes. I just assumed (I guess incorrectly!) that a freshly mixed batch of Reef Crystals would have ideal parameters...

 

[ants86]

As far as the alk, what is it just after the water change?

Tested the freshly mixed water with IO Reef Crystals, and the alk was around 10.5-11dkh. 1 hour after water change, the alk was about 8. If all the other parameters are ok, do you guys think I should continue dosing baking soda, or is there an underlying cause that I should try to fix? I run GFO and occasionally carbon, but I don't dose anything else.

 

[BigRedsReefs10]

How long are you mixing your wc water before doing the change?

 

[mr_X]

So, your current water change is bringing your water up to 8, then it's dropping to 6 by the time the next change is needed?

 

[ants86]

How long are you mixing your wc water before doing the change?

I mix it by hand until all the salt is dissolved, then usually let it sit for at least 24 hours, sometimes up to a week. Before the WC I usually mix it again with a powerhead for about half an hour while I'm cleaning the tank and doing other things.

 

[ants86]

So, your current water change is bringing your water up to 8, then it's dropping to 6 by the time the next change is needed?

I do my water changes every two weeks or so, but usually the alk drops to 6 from 8 within about a week, if not earlier.

 

[mr_X]

What test kits are you using?

 

[ants86]

What test kits are you using?

I'm using the Red Sea Reef test kit for alk, cal and mag, Hanna for phos, and API for ammonia, nitrites, nitrates and pH.

 

[mr_X]

Your calcium level sounds awful high to be from just regular water changes. Can/have you check those numbers with different kits?

 

[ants86]

Your calcium level sounds awful high to be from just regular water changes. Can/have you check those numbers with different kits?

Thanks Mr. X. I could but I'd have to find time to bring a water sample to a LFS or shell out for an extra test kit. Could it be because I don't really have that many SPS corals? In fact, my tank is made up of predominantly soft corals.

 

[mr_X]

No. I don't think so. Aren't there any reefers local to you? A reef club perhaps? NJRC has a lot of advanced folks that would have test kits.

 

[Smoothmullet]

When my alk was low 5.6 the acans showed the first sign of stress. Could be the alk if it's 6 for awhile.

 

[mr_X]

Yes, it could be, but this if it's the same time you changed out your lighting, I would say the jury is still out.

 

[Rpbustillo]

Mr. X didn't a member on here have problems maintaining alk running GFO?

 

[mr_X]

Mr. X didn't a member on here have problems maintaining alk running GFO?

Wasn't it something to do with ph? I don't remember.

 

[ants86]

Yes, it could be, but this if it's the same time you changed out your lighting, I would say the jury is still out.

Definitely agree with that statement. I made the mistake of ramping up the LED's intensity too quickly (about 2% per day from around 45% to 75% on channels), but the acans didn't start showing signs of distress until probably 2-3 weeks after I finished ramping up the lights to 75%. I was just wondering whether the low alk had anything to do with the acans' distress. As with most things that go wrong in this hobby, seems like there could be multiple causes...

The good news is that the acans don't seem to be dead, since there is clearly still flesh on them, although I feel like I see the skeletons more than I see the flesh. Just hope that they can recover if I give them more ideal conditions.

That said, are there any downsides to consistently dosing baking soda in order to raise alk? I actually think my calc is fine, since my red cap and stylophora are showing great growth, but I'll try to double check the tests when I get a chance.