Put PhosGuard in tank and dropped salinity and alkalinity

[MaxtheCat]

We got a Triton test back and it showed we had high phosphates so went to a local store and was told to use Phosguard until it dropped, then use Max Out. We put 2/3 cup in a mesh bag on Sunday after we got home. Our salinity dropped crazy fast since then from 36.4 on Sunday to 33.6 just now. And it all happened within a couple of hours. According to our Apex, it also brought our alkalinity down from 8.5 to 8.18. Why such a drastic change like this? This is scary! The salt level was high because of changing salts a little while ago and it slowly creeping up. Husband checked the salinity right after mixing and not after it settled. We wanted the salinity to come down but not this fast. Should I not keep this PhosGuard in the sump?

 

[lapin]

To quote:
"PhosGuard does not directly alter alkalinity levels. However, you may notice an indirect connection between adding PhosGuard and KH. Phosphate itself acts as a buffer in water. Lowering the amount of phosphates in your tank will indirectly affect the alkalinity levels. Obviously, because PhosGuard works to remove phosphates, you may notice a slight drop in alkalinity initially."

I have never heard of it removing salts from the water

More ref reading

FAQ: Can I use Seachem PhosGuard™ together with ________?

Another Company's product There are a lot of aquarium products on the market, and while most of them will work perfectly fine together in the aquarium, some will not. We can't 100% guarantee any p...

seachem.zendesk.com

 

[Mark Gray]

We got a Triton test back and it showed we had high phosphates so went to a local store and was told to use Phosguard until it dropped, then use Max Out. We put 2/3 cup in a mesh bag on Sunday after we got home. Our salinity dropped crazy fast since then from 36.4 on Sunday to 33.6 just now. And it all happened within a couple of hours. According to our Apex, it also brought our alkalinity down from 8.5 to 8.18. Why such a drastic change like this? This is scary! The salt level was high because of changing salts a little while ago and it slowly creeping up. Husband checked the salinity right after mixing and not after it settled. We wanted the salinity to come down but not this fast. Should I not keep this PhosGuard in the sump?

Depending how high your PO4 is you may spend a fortune useing GFOs. I like Lanthanom Chloride but go slow. It will drop your ALK. Alkalinity binds to phosphate,

 

[Randy Holmes-Farley Verified Community Expert]

While I am not a huge fan of phosguard due to the possibility of aluminum release, there is absolutely no possibility that it reduced salinity, and if there are any alkalinity effects, they are minor and short term. If you got a bigger alk drop, it was for other reasons.

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, if you actually got that large of a salinity drop for some reason (such as topping off too much), alkalinity should have dropped even more just from the salinity decrease.

 

[Randy Holmes-Farley Verified Community Expert]

To quote:
"PhosGuard does not directly alter alkalinity levels. However, you may notice an indirect connection between adding PhosGuard and KH. Phosphate itself acts as a buffer in water. Lowering the amount of phosphates in your tank will indirectly affect the alkalinity levels. Obviously, because PhosGuard works to remove phosphates, you may notice a slight drop in alkalinity initially."

I have never heard of it removing salts from the water

More ref reading

FAQ: Can I use Seachem PhosGuard™ together with ________?

Another Company's product There are a lot of aquarium products on the market, and while most of them will work perfectly fine together in the aquarium, some will not. We can't 100% guarantee any p...

seachem.zendesk.com

A tiny kernal of truth confounded by Seachem either not working this out, or just not bothering to provide exact numbers. The effect is very small: a 1 ppm drop in phosphate only drops alk by 0.03 dKH. For most people, their phosphate decline is much smaller and the alk effect is not possibly detectable.


How much might alk drop from a 1 ppm phosphate decline?

Let's calculate...

total alkalinity is defined as:

TA = [HCO3–] + 2[CO3—] + [B(OH)4–] + [OH–] + [Si(OH)3O–] + [MgOH+] + [HPO4--] + 2[PO4---] – [H+]

Chemistry and the Aquarium: What is Alkalinity?

Chemistry and the Aquarium: What is Alkalinity? - Randy provides an overview of alkalinity as to why it's important, how it's measured, and how can it be tested.

reefs.com

Thus, each PO4--- counts twice and each HPO4- counts once (H2PO4- does not count at all since it does nto get protonated in an alk titration).

How much is there?

1 ppm (1 mg/L) phosphate is 0.01 millimoles/L total phosphate

At pH 8.1, seawater contains 0.5% H2PO4–, 79% HPO4-- and 20% PO4---.

Phosphate in the Reef Aquarium

The phosphorus atom is one of living matter's basic building blocks. It is present in every living creature and in every reef aquarium's water. Unfortunately, it is often present in excess in reef aquaria, and that excess has the potential to cause at least two substantial problems for...

www.reefedition.com

Thus, we have

0.002 millimolar PO4---
0.008 millimilar HPO4--

In terms of alkalinity, we have

0.004 meq/L from the PO4--- since it is counted twice
0.008 meq/L from the HPO4-- since it is counted once

Thus, the alk from 1 ppm phosphate is 0.012 meq/L, or 0.03 dKH

Thus, a huge phosphate drop of 1 ppm will only drop alk by 0.03 dKH.

 

[MaxtheCat]

While I am not a huge fan of phosguard due to the possibility of aluminum release, there is absolutely no possibility that it reduced salinity, and if there are any alkalinity effects, they are minor and short term. If you got a bigger alk drop, it was for other reasons.

We already have aluminum in our water according to the Triton test. And he did mention to me as we were leaving the store that if I read the entire package of PhosGuard later that I would probably freak out (he knows that I stress about my animals easily) but it wasn't the kind of aluminum that gets dissolved in the water. Does that make sense?

 

[Randy Holmes-Farley Verified Community Expert]

We already have aluminum in our water according to the Triton test. And he did mention to me as we were leaving the store that if I read the entire package of PhosGuard later that I would probably freak out (he knows that I stress about my animals easily) but it wasn't the kind of aluminum that gets dissolved in the water. Does that make sense?

It is not correct that Phosguard or aluminum oxide cannot dissolve at all and add any soluble aluminum, though Seachem likes to claim this. The measured values that folks make by ICP may include both particulates and dissolved aluminum.

in any case, leather corals have a very long history of sometimes being bothered by Phosguard (this was believed when I joined the hobby in the early 1990's).

In any case, many folks detect aluminum and I would not stress over it unless leathers are closed up and/or the values exceed 0.25 ppm.