[KRB]

I have a 6 month old 40-gallon aquarium with 3 small fish only. A recent water test indicated a high (5.0) phosphate level. I can't bring it down or find out why it is so high. It's contributing to a bloom of persistent brown algae. I've recently treated for ich with ICH-X, but other than that nothing new has been added to the tank. I use regular marine flakes and feed lightly once a day. Also have done a couple water changes the past week (5 and 10 gallons) and added a phosphate sponge to the filter 2 days ago, but level is still reading 5.0. Did not have the brown algae before the ich treatments and 3 days after a cleaning it's back. Any help out there?? -- even the experts at the aquarium store are stumped.

[BubbaWPB]

What is the source of your water? Could it be high in phosphates?

[KRB]

I had my tap water tested. It was 0.

[Ninong]

What sort of phosphate sponge product are you using?

In any case, that should do the trick. You may have to replace the phosphate sponge media after several days if the phosphate levels are still high. That's because as the phosphates are adsorbed by the media, more phosphates will be released from the live rock and substrate, etc., in the tank and enter the water column.

Any of the ferric oxide hydroxide products should do the job but it may take a couple of weeks or so if you have a really bad problem.

[KRB]

I'm using Kent Marine phosphate sponge. 1 treatment for 3 days now with no change. I'll add more today. Any suggestions as to what might be causing this? I have decorative coral, lava rock, granular substrate, 1 live rock, and fish. Is it normal for phosphates to accumulate over time? The aquarium specialist said he'd never seen it so high.

[Ninong]

Your aquarium is 40 gallons and has been set up for six months. You recently tested PO4 at 5.0 ppm. Was this the first time you tested PO4? In other words, did you ever test it before and get a much lower reading? I'm trying to pin down whether it's something you added recently or if this is a problem that goes all the way back to your initial setup.

You have decorative coral, lava rock, granular substrate and one live rock. The lava rock might be the problem, it's hard to say. What exactly do you mean by "granular substrate?"

You are using Kent Marine phosphate sponge. I prefer one of the ferric oxide products myself. I don't trust anything with alumina (Al2O3). Kent Marine is activated alumina. I also don't believe their advertising disclaimer that their product will not leach aluminum in saltwater. Alumina will dissolve in saltwater in spite of what some manufacturers try to tell you. This has been proven by independent tests. The amount is very small but it is sufficient to cause problems, especially for leather corals. Since your tank is not a reef tank with inverts, it's probably not a problem but I still think one of the iron based phosphate sponge products would be safer.

According to Kent Marine's instructions, it takes one dry quart of their phosphate sponge to lower phosphate from 1.0 ppm to 0.05 ppm in a 120-gallon aquarium. I guess that means that in a 40-gallon aquarium, you could lower it from 3.0 ppm to 0.05 ppm with one quart of media.

You say that you have had this Kent Marine phosphate sponge product in place for three days now. That's longer than the maximum time recommended by Kent Marine. According to the manufacturer's instructions you are supposed to leave it for 8 hours to 2 days maximum. They warn that phosphates can be re-released into the system if initial charge is left in the system continuously.

One problem you have is that you don't really know the source of the phosphates and you have no way of knowing how high it really is because as you remove phosphates by adsorption, new phosphates will be released from "the source." This process will continue until all phosphates have been removed, however long that takes. Right now you are only measuring the phosphates in the water column, so you really can't tell yet if you are removing much because your readings are constant. Chances are that you are removing phosphates. I suggest you used one dry pint of this product at a time and change it out every 24 hours.

The manufacturer says the product can be renewed but most people who have tried this have reported that the renewed product is not very effective.

Here's what Kent Marine has to say about that:

Renewal:
For phosphate removal, renewal may or may not be possible, depending on conditions of use. At best, product may be renewed two times, depending on circumstances of use, and capacity will be much lower each time. To renew, spread 1/4" thick on a baking pan. Place in a 450 degree oven for one hour. Let cool. Rinse with fresh water and re-use. When reusing, leave for 8 hours, maximum. Do not use pan for food.

Precautions:
WARNING: PRODUCT MAY GET VERY HOT THE FIRST TIME IT IS WET! Use rubber gloves and/or place in a plastic container while rinsing!

[KRB]

You asked a lot of questions. The most important one to me is what is the source of the phosphates. I never had the phosphate tested before now, and did so only because of the brown algae. The "granular substance" is a white gravel that looks manufactured and came with the tank. I purchased the tank used -- it had been set up for 9 years. The lava rock was my addition and I got it at a very expensive aquarium-only store. It's tall and dark brown. Guess I could pull it out, clean it, and put it in a bucket of salt water to see whether the phosphate increases.

I have replaced the phosphate sponge with more. After 48 hours there was no change in the test results, so I left it in one more day. Yesterday's test looked slightly lighter, but was 4.0 at best. I must find the source because I just can't afford to use a fresh sponge every day. It's $17.50 per pint.

The ICH-X I used has formaldehyde and malachite green in it. Have you ever heard of a link between that and algae blooms?

Lastly, the store only carries this one product. Could you give me a brand for the ferric oxide? I'll start shopping around.

Thanks for your help!

[Ninong]

The white gravel is probably crushed coral. In itself, it's not a source of phosphates but it's possible that the crushed coral, assuming that's what it is, has adsorbed phosphates from some other source. There is also the possibility that this substrate (white gravel), if it was in the previous setup for 9 years, may have adsorbed phosphates from something the previous owner used and is now releasing this stored phosphate. Your phosphate levels are so high that I doubt that it could be the result of the usual culprit -- food. I really don't know what's up but I would wonder about it being caused by something in the tank???

The lava rock should not be a problem but lava rock is not something I'm all that keen on for saltwater tanks. It may be necessary for you to change out your white gravel substrate but it's hard to say for sure.

Here are a few phosphate sponge products that are iron oxide based:

Rowaphos: http://www.marinedepot.com/aquarium_...hos.asp?CartId=

Phosban: http://www.premiumaquatics.com/Merch...egory_Code=TLF

PhosLock: http://www.customaquatic.com/customa...keyresult5.asp

[huff2]

i just beat the same trouble you are having. as i read on you to got your tank s/h i did as well. i went though every product and trick in the book to remove it and it all came down to my sand bed. i got new gravel ran it bare bottom for two days all fixed.

[dragonladylea]

I just beat mine with the rowaphos and would recommend it to anyone. Not sure where the phosphates came from I have my suspicions but its gone now thanks to the rowaphos.