Target Phosphate Level

[SparKy697]

What should be the target phosphate level for my tank?

What happens if it gets too high?

Everything I read tells me 1-3ppm. My test says that I'm ~2ppm and it never seems to change. My tap water is ~.5 ppm. I'm getting signs of phosphate deficiency for the second time now. I seem to have to keep it up to 3-5 ppm in order to keep the black spots away.

 

[hashbaz]

What should be the target phosphate level for my tank?

The "rule of thumb is 1/10th of your nitrates.

What happens if it gets too high?

algae. Phosphates also affect your pH, but I'm not sure how much. You probably need a LOT of phosphates to make much difference in your pH.

I'm getting signs of phosphate deficiency for the second time now. I seem to have to keep it up to 3-5 ppm in order to keep the black spots away.

I would listen to your tank before you listen to the "rule of thumb." If your plants and algae say to add more phosphates then listen to them.

Are the black spots you refer to green spot algae?

Out of curiosity, what are your nitrates?

Also, when things seem weird, it is a good idea to verify the accuracy of your test kits.

 

[SparKy697]

I'll post a picture of the black spots when I get home tonight. They are only showing up on the stargrass, only on older leaves, and they tend to be on the tips. I do not think they are algae as those regions of the leaves seem to die off and not come back. They resemble the damage that the plant suffers when handled, almost bruise like. I had read where stargrass makes a reasonable indicator plant due to it's reaction to certain nutrients.

Deficiency Symptom
Nitrate Leaves turn pale and transparent
Phosphate Tips will turn black
Potassium Plant will stunt


Nitrates are a whole other mystery. I do water changes on Sat. and after a %50 change they read ~20. By the next day or two they are at 40 with no addition by me. Now you can read my sig below and see that I have a fair amount of fish int his tank but I also have what I consider a fair amount of plants too. I can almost not see the back of the tank and I have plants all over the place that I am letting grow out so I have some stock to move to a new tank I'm setting up. It's quite bushy in there and things are growing like crazy, still my nitrates never seem to go down.


My test supplies are a couple of months old. I have taken water to the lfs once before when I didn't trust my own and they came up with the same answers. Maybe it's time to check again.