DIY Phosphate Additive

Drew Halliday · Apr 23, 2020

I have a tank that has been set up for 10 weeks now and I added a bunch of SPS. I figured I would add corals first and let the tank go fallow for the ich quarantine period since I can't get fish anyways and I am going crazy. I can't get the fish I want because of the virus and now I am in a situation I have never been in before. I have to dose for nitrates and phosphates. The nitrate read 0 and the phosphate read 0.00. I ordered stuff online but because of the virus prime may take up to a week.

I had some gross water in the live rock tote from my last tank. I boiled that to remove ammonia and added it slowly. Gross, I can't believe I did that! The corals liked it though they stopped bleaching and started extending their polyps more. Phosphate got up to .03 on Monday but it is now back down to .01 as of yesterday. Surprisingly nitrate was still at 0 though and I found some stump remover to get me by.

I have been trying to find something local to get me by for phosphates. I did some wikipedia searches for sodium and potassium phosphate and found it was in baking powder (if it is not sold out. IDK why it has been). Someone also mentioned adding baking powder in an older post but they didn't say if they had tried it. Some has aluminum or corn starch and I don't want to add those to the water. Although I may be able to filter out the cornstarch.

The Market Pantry brand (target) seems to be the best from an ingredients stand point. The ingredients are: Calcium Carbonate (what corals are made of, may not dissolve) , Sodium Acid Pyrophosphate (phosphate source), Sodium Bicarbonate (baking soda, I add this anyways), Monocalcium Phosphate (possible calcium and phosphate source).

Has anyone added baking powder, intentionally? Does anyone see a reason this would not be good to add other than some cloudiness?

Thanks

P-Dub · Apr 23, 2020

Never tried baking powder. Greenleafaquariums.com has, and I use, their Monopotassium Phosphate and Potassium Nitrate for my additions... FWIW.
@Randy Holmes-Farley...

Rick.45cal · Apr 23, 2020

You can order food grade tri sodium phosphate and use that to make a solution.

P-Dub · Apr 23, 2020

Rick.45cal said:
You can order food grade tri sodium phosphate and use that to make a solution.

Food grade TSP on Amazon, 12 oz =$18.00. Monopotassium Phosphate at Greenleafaquariums, 1lb = $4.00....

Drew Halliday · Apr 23, 2020

@P-Dub @Rick.45cal I think I ordered that exact one yesterday but even with it being prime amazon said it might not be here for a week. I just need something to get me by until then.

Randy Holmes-Farley · Apr 24, 2020

Some baking powders may be OK, but I'd advise against them. .

The one I have in the kitchen (Davis Double Acting Baking Powder) has corn starch as the first ingredient (probably OK, but might drive bacteria or cloud the water) and third (before monocalcium phosphate) is sodium aluminum sulfate, which I wouldn't want to add. I'm also not certain one can dissolve this in water before use without the phosphate precipitating as insoluble calcium phosphate.

Drew Halliday · Apr 24, 2020

Randy Holmes-Farley said:
Some baking powders may be OK, but I'd advise against them. .

The one I have in the kitchen (Davis Double Acting Baking Powder) has corn starch as the first ingredient (probably OK, but might drive bacteria or cloud the water) and third (before monocalcium phosphate) is sodium aluminum sulfate, which I wouldn't want to add. I'm also not certain one can dissolve this in water before use without the phosphate precipitating as insoluble calcium phosphate.

The aluminum and starch are why I went with this particular brand because it doesn’t contain them. I used acid to dissolve the calcium carbonate and calcium phosphate so that I am sure I don’t have any phosphate precipitates lurking in my tank.

I dissolved 1.25 tsp or 7.5g market pantry baking powder in water and added sulfuric acid until it just began to clear (about 5ml). I dripped this into the tank (about 200gal) overnight.

For the sake of science here are my embarrassing results:

An increase of calcium by 10ppm
An increase of alkalinity by .2ppm
An increase of phosphate by 1.20ppm

Obviously I don’t want my phosphate that high. (API phosphate test kits are useless) Now I will have to order some algae, hope my dry rock soaks it up and get the GFO reactor going. Do high phosphates justify an emergency water change or should I bring it down slowly?

On the positive side here is a local, DIY phosphate additive for a dollar.

Randy Holmes-Farley · Apr 24, 2020

Where'd you get sulfuric acid? It's not a usual home item.

I'd watch the phosphate for a bit and see what happens naturally.

Drew Halliday · Apr 24, 2020

Randy Holmes-Farley said:
Where'd you get sulfuric acid? It's not a usual home item.

I'd watch the phosphate for a bit and see what happens naturally.

I had it on hand from another project. I got it from O’riley or Autozone. From what I have heard virgin battery acid is just short of acs grade. It needs to be pure to keep the battery functioning properly.

I guess now that I am telling everyone where to get it I should tell everyone don’t play with battery acid unless you have training on how to handle it.

Drew Halliday · Apr 28, 2020

Update on the mix that I did not use acid to dissolve the calcium carbonate. It has finally precipitated out. So if you want to use this baking powder without the acid you will have to wait a few days for it to settle or it would cloud your tank. When I have to dose again I will use this stuff and update the results.

Yehuda Dana · Oct 13, 2022

I used Monopotassium Phosphate (KH2PO4) to raise my Phosphate level on SPS dominant reef tank.

Actually, I miscalculated the amount needed to be added by mistake...
So for the last week or so, my PO4 level is above 2.5 (!!!).
Even though, no any bad effects on the corals...

How come?
I thought it will make them brownish... but color remains good as it was

Randy Holmes-Farley · Oct 13, 2022

Yehuda Dana said:
I used Monopotassium Phosphate (KH2PO4) to raise my Phosphate level on SPS dominant reef tank.

Actually, I miscalculated the amount needed to be added by mistake...
So for the last week or so, my PO4 level is above 2.5 (!!!).
Even though, no any bad effects on the corals...

How come?
I thought it will make them brownish... but color remains good as it was

If phosphate is not a limiting factor for the zoox, then it won’t likely cause browning.