# Phosphates gallore!



## Emily6 (Feb 14, 2006)

Hi, I posted earlier regarding phosphates in my 10g. tank. The tap water alone contains high phosphates (up to 2.5 mg/L) but even after removing them via phosphate sponge filter media (and not topping off the tank), phosphate levels still rise back up to 2.5-5 mg/L. I recently switched to El Natural but the problem was present even before that. Any thoughts? My tank has 10 1" sized fish and a mystery snail. I tried to reduce feeding but I fear starving the fish and the substrate.


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## aquabillpers (Apr 13, 2006)

What substrate do you have? Batches of Eco Complete were contaminated with phospates a while ago.

bill


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## hoppycalif (Apr 7, 2005)

Measuring phosphates accurately isn't easy, so you have to calibrate your test kit if you want to depend on it for accuracy. I don't think 2.5 ppm of phosphates is excessive in any case.


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## Emily6 (Feb 14, 2006)

Right now I have a layer of organic potting soil underneath a layer of fine gravel. I sprinkled less than half a cup of laterite between. No, 2.5 isn't so bad but that's just what's coming out of the tap. My tank easily reaches the limit of my test kit without interference. How would one calibrate a test kit? I've never thought of that before. Thanks for the interest!


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## hoppycalif (Apr 7, 2005)

To calibrate a test kit you need to get some distilled or DI water and some KH2PO4 (for a phosphate test kit), then calculate the amount of KH2PO4 to add to a liter of water to arrive at some specific ppm of PO4. That will likely be a concentratiion far above the range you are interested in. Then dilute this with more distilled or DI water to get down to a calculated value near the top of the range of interest. Check that with the test kit. Dilute the water again with distilled or DI water to drop the ppm of PO4 in half. Repeat the testing with the test kit. Etc. This tells you if the test kit is accurate, and gives you a chart for what a test kit reading really means. The hard part is figuring out how much KH2PO4 to add initially and weighing out such a small quantity accurately.


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## dwalstad (Apr 14, 2006)

I wouldn't be that concerned about phosphates at 2.5 ppm. Phosphates are totally harmless to plants, fish, and humans. They have been tied to excessive algae growth, but that's hardly something to get upset about. I think excessive iron would stimulate algae in most aquariums more than phosphates. In fact, excess phosphates will reduce water iron levels (the two form iron phosphate precipitates), which is probably a good thing. 

If your plants are growing well and the fish are healthy, I would rejoice and relax.

Folks, let's worry about what will really cause problems for our fish: nitrites, ammonia, hydrogen sulfide, and lack of oxygen (fish gasping at the surface). 

For plants, it would be a lack of hardwater nutrients.

Diana


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## Emily6 (Feb 14, 2006)

Thank you for the advice. The fish are doing alright but I do have moderate algae growth and slow-growing plants. I'm trying to avoid dosing the tank with liquid fertilizer, back to Diana's thought regarding reduced iron up-take. That was my concern with the high PO and slow plant growth. I was also worried about the source of PO within the tank- perhaps implying deeper issues. I'll let things be for a bit and see.


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## dwalstad (Apr 14, 2006)

Slow plant growth or a tank with slow-growing plants is always a problem. If the plants don't grow well, then algae will fill the vacuum. Algal growth almost always inhibits plant growth (removes CO2 that submerged plants badly need in an El Natural tank). 

It's always a balance between plants and algae. Our goal as plant enthusiasts is to tilt the balance towards the plants. This can be done by using a rich substrate with nutrients plant roots can tap into that algae can't or using floating plants that can tap into air CO2 and strong surface lighting.

If you don't have floating plants and have adequate light, you might consider adding floating plants. These plants have the "aerial advantage" over algae that I describe in my book. In a way, emergent plants protect submerged plants from algae. If the floating plants grow well, they will also mop up those phosphates.


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## Emily6 (Feb 14, 2006)

I do have floating plants (amazon frogbit) and they're during spectacularly- I remove fistfuls each week in a 10g. just to open the surface a bit. Previously you suggested (via email) that I remove the CO2 and reduce the lighting to cut back on excess (I have a Hagen fermenting canister and 28watts of full spectrum). While I wouldn't describe the algae as booming, I still have several varieties that have covered basically every area that doesn't get shaded by plants (gravel, drift wood, glass...) Even the surfaces of leaves are getting gross. This is after about 2 weeks letting the floating plants take over and the CO2 removed. Sorry to belabor this one but it's still a headache for me. :-/ Thanks for your time!


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## dwalstad (Apr 14, 2006)

Sorry, but I lose track of who I've corresponded with earlier.

That's great that the Frog Bit is doing well, and you are continuously removing excess. Your comment that algae is "growing everywhere that isn't shaded" is interesting. I would try to keep a fairly dense cover over the tank until you get the algae under control. 

If the substrate is new (less than 6 weeks), it is probably giving off a lot of nutrients that are stimulating the algae.

Do you still have 28 watts of CF light over your 10 gal tank? For a 10 gal (only 10 inches deep), 15 watts of ordinary (T-12) fluorescent light is plenty.

Please don't hold back on the fishfood. If you've got more than 1 ppm phosphates, extra fishfood isn't going to make that much difference. Your fish will thank you.

I know its hard for people that are used to high-tech tanks, but I would just maybe wait this one out. If your submerged plants don't start perking up, you could think about a "replanting" in a few months. It's possible that your substrate will be conditioned by then so that new plants will fair better. 

I wouldn't give up on this tank. Send us a picture if you have time.


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## Emily6 (Feb 14, 2006)

*Tank on the mend- irrate tank mates!*

Funny thing- right after that last reply, I ran a battery of tests on my tank and everything except PO came back fantastic! And the algae isn't growing quite as vigorously. I replanted an ozelot sword in the center to shade out a bit of the algae-covered gravel and went back to my 15w. fixture.

Oddly, my two long-finned blue danios have gone bazerk and are chewing my other fish to shreds! They seem a little bloated- maybe breeding condition? Anyway, I put them in the time-out tank alone until things calm down. Any thoughts?


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