PO4 to NO3 Ratio?

Planterson

Junior Poster
Sep 11, 2015
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Does PO4 to NO3 need to be 1:4? I ask because I'm developing GSA of all things, on the glass particularly, as well as on some stone. Want to nip it in the bud.


I've heard that it's generally caused by low phosphates, and I'm already dosing EI levels. So if I want to up my phosphate do I need to simply increase the entirety of my dose, or can I throttle up on just PO4? Right now I dose these levels 3x a week:


NO3 7.45


N 1.68


PO4 1.84


P 0.6


K 5.46


This is a solution, so can I just mix more PO4 into it? Or do I simply need to up the entire does? Considering bumping it up to 2.0


How high can I safely raise PO4 as it relates to NO3?


My testing shows 1.0~ PO4 before a water change. I have not cross-referenced the test against a known standard, I just assumed the colors were relatively accurate.
 

Planterson

Junior Poster
Sep 11, 2015
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Welp, scratch this whole post. I calibrated my PO4 kit. It was DRAMATICALLY off. Apparently the test kit is completely screwed up, it's not expired, but no idea where my phosphates are.


I'll come back today and update this topic.
 

Pikez

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May 12, 2013
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If you are dosing EI, EI lite, or even PPS, you are not deficient in P. Ratio of P to N makes no difference, as long as plants have adequate levels of both. Generally the ratio is about 5 to 10X more N. Adding more P will make no difference with GSA.


'Low P causes GSA' is a myth IMO.


You can add more P. No harm in that at all. More P will NOT cause more algae.


What will help is stabilizing the tank - giving plants everything they need to grow in a consistent, stable, and even levels, starting with CO2. Reduce light to make sure you are not all over the place with CO2. Stabilize CO2 during photoperiod, reduce light, do regular water changes to reset the tank, dose consistently, clean and maintain the tank religiously. Do this over and over and over.


Back in the day, when I got cyano or GSA, I used to quickly goggle 'cause of BGA' etc. and end up with all kinds of false or useless conclusion. What works is getting plants to physically grow. I still occasionally get algae. And when that happens, I don't google for cures anymore - I do what I described above. It goes away in about 2 weeks.


Test kits are fun, in and of itself. But don't really solve issues. Resetting with a big water change does.
 
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Planterson

Junior Poster
Sep 11, 2015
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For reference, here's what I'm seeing. Would you consider this "normal," only needing manual scrubbing, or a sign of a tank in decline?





You can see some on the lily pipe in this shot (above).





Some here on the rock, and a bit on the Stauro.


I appreciate the feedback, the amount of GSA I have is almost nil, this is a "nip it in the bud" scenario. Will excessive PO4 to NO3 not cause any uptake issues? I know there is a relationship between some of these nutrients (like K to P uptake), was wondering if that applies here. It seems a deficiency in one macro could certainly limit uptake of another, is this not accurate? Part of coming here is to find out the right information. Is there not a general guideline (ie 10x to 1 P to N)? Tank maintenance is regular, 50% WC every week, 75% every third change. Constant trimming.


From the response, it's implied that I simply don't take care of my tank, which isn't true. I put a lot of time, care and attention to the tank. Light was painstakingly throttled to the point where I don't see "leggy" growth, Co2 is probably too high, but my plants pearl like airstones. I figured that these were in a good place, which is why I'm asking about ferts, but I can certainly try to adjust them further if that's the general concensus.
 
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Pikez

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Pretty!


I think this is just a minor imbalance. You can get back on track easily. Hard to gauge poster skill without pics. (Still, fun to rant on about pet peeves! :)) You're on top of things.


The only possible issue I can think of with excessive P is that it may precipitate some Fe. Even that is questionable. P is one of those things that plants suck up really fast and react quickly to. If you're doing EI or even in the vicinity of EI, your dosing ratios from online calculators are fine. As far as generally accepted ratios, I think you'll get a lot of head-nodding with 10:1 ratio of nitrate/ Phosphate. You can only get really accurate if you're talking about individual species needs, but no one really knows that stuff and there is no need to in mixed species tanks.


Yeah, I get the 'leggy' growth thing and countering that with higher light. Sometimes, legginess is a plea for more CO2. May be not in this case. Legginess often gets plants to the surface quickly where they can float and soak up 400 ppm CO2 all day long. The problem with increasing light is that you're accepting to walk a tightrope. I have far fewer setbacks after lowering light. It's a compromise.


I'd focus on light and CO2.
 
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Planterson

Junior Poster
Sep 11, 2015
59
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I certainly appreciate any and all feedback, Pikez. I understand what you mean, though. There are a flood of "I have algae!! HALP!!" posts to deal with... and I generally provide a somewhat "canned" response myself, since 9 times out of 10 the issue lies in general maintenance. I come here when I want REAL advice, haha.


Really, it's not so much of a question on the GSA as much as wanting to know if there is indeed any validity to the suggested P to N ratio. I figured that might be the motivation for so many to suggest low phosphate, not for the reason that low phosphate in and of itself causes the GSA, but the fact that another nutrient might be limited by its absence or something of that nature. But if the ratio is nonsense, then that does indeed answer my question :)


I will revisit light/co2, but boy that's a battle I didn't want to have to engage in again, lol. Clearly it's still not as tuned in as it could be. There might be some points on the dial for co2 increase, but my reactor is a bit undersized and has trouble keeping quiet with higher Co2 levels. So I suppose I'll knock the light down a bit. It's on a 6 hour photoperiod as it is though.