Does adding salt raise phosphate number?

[SueAndHerZoo]

I've been addicted to this hobby for many years but I never was one to chase numbers. If things looked happy, I was happy. But lately I've noticed my 72 gallon is looking pretty ugly so I did some testing: phosphates were 1.69! I got some Phosphat-E to start bringing it down, but today decided to check one of my other tanks just out of curiosity. It's reading 0.68 and it's practically an empty tank. It has ONE tiny seahorse (not even 2 inches) and one diamond goby. It's certainly not overstocked and I don't overfeed, so I'm puzzled. So I went down to the basement to test the water in the RO/DI barrel and also the water in the salted RO-DI water. Unsalted RO-DI water was 0.00, but the salted water was 0.07.

Does salt add some? Or does that barrel need to be emptied and scrubbed or something? I'll treat all 3 tanks with Phosphat-E but I would prefer to understand where the phosphate is coming from and not have to use chemicals regularly to keep it down.

I'm stumped.
Sue

 

[tzabor10]

What is your export system?
Salt should not contribute to phosphate significantly

 

[Fish Fan]

Phosphate binds to and can be released by rock and sand, so the rocks in your tank may be leaching phosphate, which may be why it’s high in your tank. Freshly mixed saltwater shouldn’t have phosphate so if you’re seeing some in your mixing bucket, it could be that there’s some organic in there too.

 

[SueAndHerZoo]

What is your export system?
Salt should not contribute to phosphate significantly

In the 72 gallon where the phosphate was over 1.0, I have a sump, tons of cheato growing in it, and a protein skimmer. in the 55 gallon that has hardly any livestock I have an oversized canister filter and a protein skimmer.

 

[SueAndHerZoo]

Phosphate binds to and can be released by rock and sand, so the rocks in your tank may be leaching phosphate, which may be why it’s high in your tank. Freshly mixed saltwater shouldn’t have phosphate so if you’re seeing some in your mixing bucket, it could be that there’s some organic in there too.

So if the rock/sand is too old, that could be the problem? Because the sand is definitely very old, most of the rock is between 1-5 years old.
Sue

 

[Fish Fan]

So if the rock/sand is too old, that could be the problem? Because the sand is definitely very old, most of the rock is between 1-5 years old.
Sue

I don't think it's a problem, just something to be aware of.