Constant High Alkalinity and Phosphate

[uscggirl]

Hello everyone. I have a situation where my Alkalinity and Phosphate stay high. I’ve tried to read all the posts having anything to do with Alkalinity, but it seems most people want to keep it raised, while I’d like to get it lower. I’ve tried dosing some vinegar, and that helped for a day, but it went way up again. From 11.8 to 13.9 in under 16 hours. My Salinity and Ph stay stable at 1.025 and 7.8 respectively. I’d like to increase Ph, but want to get the Alkalinity sorted first. I am new to saltwater and spent a few years with freshwater. I’m only running a 10 gallon tank with HOB and UV filter for now while I learn and make plans for tank size and equipment. Other parameters are pretty much on target with Calcium finally rising from 348 on April 6, to 480 today. I’ve read I need to stop dosing, but I haven’t dosed anything. I do have some Phosguard in my HOB in hopes it will lower Phosphate. Not really helping though. Any ideas or suggestions are most welcome! Stock is currently 2 clowns, 3 yellow damsels, 1 blue damsel, and emerald crab If that helps. I’ve been doing a two gallon water change every other day.

 

[Hermie]

what is the alkalinity of your replacement saltwater? the two gallon every other day

 

[Hermie]

delete

 

[Uncle99]

Ensure MG is on point in the 1300-1400ppm or Alk will run all over the place.
Unless your using a Hanna ULR Phosphorus checker, many hobby grade tests for Phosphate are way off.
I had a test show .25ppm, stable, would not move even with GFO, turns out, kit can’t read below .25ppm.
The actual was 20ppb, or say 0.06ppm.

 

[uscggirl]

what is the alkalinity of your replacement saltwater? the two gallon every other day

Thanks for asking. I tested my replacement water this evening just to be sure it’s not that. I’ve been using premixed saltwater (Natures Ocean) so I wanted to ensure it wasn’t messing me up! I’m using Hanna Checkers and the parameters for the premixed water are:
salinity - 1.027
Ph - 7.72
Phosphate - 0.05
Alk - 7.7
Calcium - 480
i made a mistake in my post, my Calcium in the tank is 403, and in the replacement water 480.

 

[uscggirl]

Ensure MG is on point in the 1300-1400ppm or Alk will run all over the place.
Unless your using a Hanna ULR Phosphorus checker, many hobby grade tests for Phosphate are way off.
I had a test show .25ppm, stable, would not move even with GFO, turns out, kit can’t read below .25ppm.
The actual was 20ppb, or say 0.06ppm.

Thanks for the magnesium hint! I just received my Salifert Magnesium test kit, so I’ll add that to my daily checks. I’m using Hanna checkers for the others, and the ULR for Phosphate.

 

[uscggirl]

My Alkalinity was up to 20 one day, which is when I dosed vinegar. I’d prefer to figure out the source however, so I don’t just treat the problem. My premixed saltwater says it has some sort of buffer to maintain Ph. Could that buffer possibly impact my Alk and Phosphates?

 

[Hermie]

Something is weird

 

[uscggirl]

How are you testing the alk?

I’m using a Hanna Alk checker. I’m always careful to do the tests accurately, and to ensure I don’t have residual water getting mixed in.

 

[uscggirl]

The Alk in my premixed saltwater tested out fine at 7.7, so I’m not sure what causes it to increase once it’s in the tank. I’ll check magnesium when I do the rest tomorrow, but it’s just weird that Alk goes so high when it’s low in the new water I add.

 

[Hermie]

The Alk in my premixed saltwater tested out fine at 7.7, so I’m not sure what causes it to increase once it’s in the tank. I’ll check magnesium when I do the rest tomorrow, but it’s just weird that Alk goes so high when it’s low in the new water I add.

what should happen is, when you change water with lower alk than the tank's current alk, the alk will proportionally go down; so you should do an alk test immediately before water change, test the alk of the new salt water, then do the water change, then test the alk of the tank and all those numbers should be correct. Then you will know that doing water changes will reduce your alk over time.

 

[uscggirl]

what should happen is, when you change water with lower alk than the tank's current alk, the alk will proportionally go down; so you should do an alk test immediately before water change, test the alk of the new salt water, then do the water change, then test the alk of the tank and all those numbers should be correct. Then you will know that doing water changes will reduce your alk over time.

I’ll check in the morning before the water change, and then after as well. I think what I’ve seen when I test after is that it goes down as expected, then edges right backup again. I’ll try to keep better track of times of day as well as check Right before water changes.

 

[DrMMI]

Do you have any large coral skeletons in the tank? A friend of mine gave me a large acro skeleton to put in my tank and my alk shot up to 13 and stayed there for weeks without the need to dose.

 

[uscggirl]

So I decided not to wait til morning, and since I had done a water change about 6 hours ago I tested again, this time with Magnesium as well. Magnesium is at 1440, Phosphate 0.21, and Alk 12.3. Will check again in the morning.

 

[uscggirl]

Do you have any large coral skeletons in the tank? A friend of mine gave me a large acro skeleton to put in my tank and my alk shot up to 13 and stayed there for weeks without the need to dose.

No coral skeleton, but thanks for your info! I have one rock from LFS, and one Carib Sea life rock. Maybe from the rock I got at the LFS? It was in their coral tank although it’s definitely not a coral skeleton.

 

[uscggirl]

Updates on my testing. The magnesium number I got last night with the Salifert test is a bit high. Operator error! There are just so many ways that test can go wrong, it would be nice to find a more accurate test. At any rate, things are looking up. Here’s what’s transpired since last night...
11 April @ 1415
Salinity - 1.027
Temp - 81.7
Ph - 7.68
Phosphate - 0.65
Alkalinity - 12.8
Calcium - 375
Magnesium - 1230

After these tests, I did a 30% (3 gallon) water change primarily due to increased ammonia at 0.25. I also pulled the Aquaclear 50 HOB filter stack, cleared a bunch of clear slime out, tossed the Seachem Phosguard and the filter floss, added new sponge, activated carbon bag, and a piece of Fluval Phosphate remover for their canister filters that I cut to fit the HOB. I kept the bio balls that have been in there from the start. Wanted to let it run a bit before testing again, and the temp needed to get back on track after the water change. So, subsequent testing is as follows:

11 April @1800
Salinity - 1.026
Temp - 80.4
Ph - 7.84
Phosphate - 0.26
Alkalinity - 11.8
Calcium - 412
Magnesium - 1200
I‘m relatively pleased with the overall numbers. My Alkalinity isn’t 20 anymore, and while my Phosphates are still high, I’m hopeful they’ll adjust downward. My Calcium is back up to a good level, and my Magnesium is stable considering the variability of the testing kit vs testor. I’ve been over feeding in hopes of increasing Nitrates, but no luck so far. I think my Emerald crab cleans up too much of the leftovers! Then again, the ammonia did go up, so either the residents are peeing a lot, or I have too much food lying about. Thank you all for your comments and suggestions!! I’ve been reading all the great chemistry articles by @Randy Holmes-Farley, and trying to get right with all the interactions. Hopefully my tank will get here soon so I can get my babies out of the 10 gallon that was initially intended as a QT. I’ve added sand and rock to make it more homey while we wait, but these guys need a real home!

 

[Dan_P]

My Alkalinity was up to 20 one day, which is when I dosed vinegar. I’d prefer to figure out the source however, so I don’t just treat the problem. My premixed saltwater says it has some sort of buffer to maintain Ph. Could that buffer possibly impact my Alk and Phosphates?

The buffer might interfere with the alkalinity test.

 

[Rmckoy]

Seams so weird to have high alk . With the source water being 7.7

you haven’t added or dosed anything to the tank other than water changes ?

 

[Uncle99]

1200 MG is too low IMM.
1360 is min and I run 1410.
Up to 1500 is fine, it won’t hurt nothing.

 

[uscggirl]

The buffer might interfere with the alkalinity test.

That’s good to know. I’m confused though because I tested the replacement water and the Alk was 7.7. I figure if the buffer would interfere with the test, maybe it would there too? But I’m clearly not an expert, so who knows?