Can't get Phosphates under control

[NadiaG]

My phosphate levels are super high.

I noticed an increased diatom grow and never owned a PO4 test before. Did some research and looked like I had to get a test. Bought an API PO4 test kit. First readings, around 3.0 ppm!!! Almost had a heart attack... Did a 40% PWC (besides regular 25% weekly), cut down on flake and other phos high foods, cleaned off some diatoms with hydrogen peroxide solution. A week later my reading is at 1.0 ppm... And can't get it any lower.... Please help!! I'm running out of ideas..
Oh and I got a phos-zorb, but can't fit it into the filter, so it is hanging in a bag next to it. That helped to reduce the levels too but still not enough.. What else can I do? Thanks

 

[Old Scales]

To offer some suggestions, we need to know some details. Tell us what size tank, what type light, what is your substrate, is it a tank with plants(a few or a lot). How long do you leave lights on. How long has tank been set up? Then we can go from there. OS.

 

[NadiaG]

It's a 10g freshwater tank with tetras, a catfish and a nerite snail. Has been running for 4 months now. Lights are on timer, 6.5 hours of 15w full spec fluorescent and 15w pink incan, ones these go off a blue led kicks in for another 6 hours.

Water is tested weekly, consistent of
Ammonia 0
Nitrite 0
Nitrates 20

Not sure of the name of the substrate but it is gravel and it is vacuumed weekly with 25% PWC.

Some plastic plants present but also have anubia nana, broad leaf ludwigia and microswords. And a marimo moss ball. Dosing weekly with API leaf zone and daily with seachem excel ( all recommended by users of this forum). No other ferts are used. Plants are doing well.

 

[NadiaG]

So is fish!!!

 

[Old Scales]

Well, I'm not sure why you are upset about the PO4 being at 3 ppm. Are you having algae issues? I bet running 6.5 hrs with those lights is working well and you don't mention algae. PO4 is not toxic to fish like NO3 can be. If you do regular 40-50% WC's your phosphates should not become a problem. Sounds like you may have got some bad advice. I know the ludwigia will appreciate the PO4. I have a high light, high tech heavily planted tank and I keep my PO4 at 3-5 ppm on purpose with no ill affect on my fish and no algae. I run my lights at 6.5 hours also. What problems are you having? OS.

 

[NadiaG]

Diatoms! Can't get rid off them... My snail eats it on the walls and rocks but can't really get to each leaf of the plants to munch on it. Ludwigia is growing well but seems to get that brown algae on leaves towards the bottom and anubia gets it too.

 

[Old Scales]

OK, diatoms are caused by excess silicates in your water. Four months is about right for them to rare their ugly head. Once the free silicates in your substrate are consumed by the diatoms they will disappear. If it is a brown slime that rubs off your plants and stuff easily, it's diatoms. To help fight it, rub as much off as possible right before you do your WC then try and suck up as much of it as possible. PO4 doesn't have much to do with diatoms. Good thing is that once the diatoms are gone they usually stay away unless you do a massive substrate change. Sorry, it's one of the pains of newer tanks. OS.

 

[NadiaG]

Grrr! Hate them. I do try to clean them off as much as I can and my snail helps me too. Hope they go away soon, it's been almost a month now... Thanks for the tips

 

[Old Scales]

Your welcome and good luck. See you around. OS.

 

[Tinadno]

You may want to consider using reverse osmosis water instead of your tap. This is seen more in reef tanks. Your tap water will always have phosphates in it so your introducing them into your tank with every water change. With using reverse osmosis you have better control of what is in your water. Also I would try using Chemi-pure elite for your carbon. Hope this helps

 

[NadiaG]

Unfortunately, RO is way out of my budget.. But I will do research on chemi-pure. Thanks!

 

[Old Scales]

Test your tap water after letting it sit for 12+ hrs. Do all the tests you have and record somewhere. This is the baseline you know you're working from. Test your tap water now for winter then test again this summer. Many supplies change a little during extremes of seasons. Most municipal water treatment facilities have to meet federal standards for how much nitrate and phosphates can be in the public's water. Unless exempted by permit because of unusual geological conditions of a region, the standard is really low.
Ours for PO4 was .03ppm. Hope this helps. OS.