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Discussion Starter · #1 ·
On the internet forums, I'm led to believe that phosphates are good for plants.

The manager of my LFS, who usually gives pretty sound advice, says they're bad. He also told me he used to work in a plant nursery and the only time they dosed phosphates was when they wanted plants to flower. Otherwise they just cause algae.

I measured my PO4 today, and mine are high! they are 4. Or 3, depending if I'm reading the chart right, I wasn't sure. But anyway, they're over 2 which was the highest I wanted to see.

It looks like my plants aren't using them up that quick, and my algae is getting a bit worse again.

I'm using PPS pro. This is my tank, as you can see the plants aren't completely grown in yet. Although, this photo was taken a few weeks ago and the plants are definately taller than they were then.


I did a 1/3 tank water change today, with RO water in case theres phosphates in my tap (with extra kh liquid - Kent ph buffering stuff - I raised the kh to 4dkh).

So... why are phosphates good?
 

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I'm not much of a scientist (not one at all unless you count this hobby), but I know that when I went lean on phosphates, I had bad GSA issues. When I went heavy on phos, GSA went away.
Phosphorus is one of the 3 major nutrients a plant needs to live and grow. Of coarse it's neccesary. It needs to be dosed in balance with the other macros (N,K) and micros.

If you are having algae issues, there is more than just a phosphate issue.

-Dave
 

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If you are having algae issues, there is more than just a phosphate issue.
meaning...too much phos in relation to the other macros, or too much micro and too little macro, or any of those and too long/short a photoperiod...lots of factors. But certainly phos is needed for plant growth just as nitrogen and potassium are needed.

Here's a quote from an Ag website:
"Particularly, phosphorus is a major building block of DNA molecules. It is responsible for the storage of energy in the form of adenosine diphosphate (ADP) and adenosine triphosphate (ATP). The energy stored in these phosphate compounds allows for the transportation of nutrients across the cell wall and the synthesis of nucleic acid and proteins."
 

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Discussion Starter · #4 ·
Can high nitrates cause algae issues? Because mine are rather high approx 50 I think maybe a bit lower, like 40. - I've lost my colour chart for my test kit.

I'm wondering whether I need to be dosing more micros, because my java fern is showing signs of deficiency - new growth is see through around the edges, and yellowing after a little while (days).
 

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Algae generally starts when the plants are not growing well enough to maintain zero ammonia in the tank at all times. Having an excess of any of the fertilizers we dose has not been found to start an algae bloom by those who are good enough at doing controlled experiments to be able to determine that. More often than not it is a shortage of CO2 or fluctuating concentration from day to day that leads to slow plant growth which leads to the ammonia from the fish and other biological processes building up slightly, triggering algae to start growing. Of course this hobby is still evolving, so it is entirely possible that some day someone will find that some combination of high nutrient level, along with something else may also start algae growing. That hasn't happened yet to my knowledge.
 

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Discussion Starter · #7 ·
If I didn't use my pH buffer, wouldn't my KH be really low, hence not good for stable CO2 levels?

Thanks for all your replies, they've clarified things for me. Phosphates are a good thing, and my algae is probably because my tank is still settling in.

I've found my algae is a little better today, after the water change yesterday.
 

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If I didn't use my pH buffer, wouldn't my KH be really low, hence not good for stable CO2 levels?
There is no need for any pH buffer in planted aquariums. It is the same for KH, no need, fish and plants don't care about KH. Less chemicals you use better. Important is Carbon, plants need Carbon from CO2. It can be supplied at a stable bubble rate at one bubble per second for medium size aquariums.
 

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Discussion Starter · #12 ·
I'm using pressurised CO2. I'm not sure how many bubbles a second, but my drop checkers (one on each end of the tank to ensure CO2 is being circulated - it's a big tank!) are green with 4dkh solution in the drop checkers so 30ppm.

My plants have taken off in the last few days. There's a noticeable difference. No idea what triggered it... maybe things are settling in? Even one of my crinium callimistratums, who's leaves were starting to rot, has made a come back!
 
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