# Increasing the PO4 in DIY TPN+



## Egmel (13 Jun 2008)

I'm going to be making a batch of James' DIY TPN+ this weekend.

Now the current view on TPN+ is that it's a good all round fertiliser but that it works best for people who have high phosphates in their tap water.

I looked at the water report for my area (PDF) but couldn't see any mention of phosphates at all.  However I am suffering from quite a bit of GSA which I'm lead to believe is linked to PO4 deficiency.

I'm currently dosing 5ml of TPN+ and 2.5ml of EasyCarbo a day on a 70l tank with DIY CO2.  I have 45w T8 lighting split into 15w dawn/dusk and 45w full light.  Dawn - Dusk ~10hrs and full light for ~8hrs.  I change minimum 30l a week.

Would it be worth increasing the PO4 in the DIY TPN+ I'm making this weekend and if so by how much and what's the easiest way of doing it.  Increase the Potassium Phosphate to about 4g?


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## ceg4048 (13 Jun 2008)

A high light 70l should receive just under a gram of KH2PO4 per week (3 doses) so I would just figure out how many doses of TPN+ you've got left in your bottle and add the appropriate number of grams dry powder to the bottle. Alternatively just double your dosage of TPN+ and wait 3 weeks to see if that helped. If not then double it again.

Cheers,


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## Egmel (13 Jun 2008)

ceg4048 said:
			
		

> A high light 70l should receive just under a gram of KH2PO4 per week (3 doses) so I would just figure out how many doses of TPN+ you've got left in your bottle and add the appropriate number of grams dry powder to the bottle. Alternatively just double your dosage of TPN+ and wait 3 weeks to see if that helped. If not then double it again.


Ok, well I've got about a 2 x 5ml doses of true TPN+ left so maybe not that way.

But at 5ml a day, that means the 500ml recipe on James' page should last me 100days ~15weeks which would mean I need to change the KH2PO4 from 2.2g to 15g!  
My weekly dose would then be
3.5g Potassium Nitrate
1g Potassium Phosphate (monobasic)
1.25g Magnesium Sulphate Heptahydrate (Epsom Salts)
~0.5g Aqua Essentials Trace Elements Mix

Alternatively I could increase it to 7g and dose 10ml a day.
My weekly dose would then be
7g Potassium Nitrate
1g Potassium Phosphate (monobasic)
2.5g Magnesium Sulphate Heptahydrate (Epsom Salts)
~1g Aqua Essentials Trace Elements Mix

I can always increase the concentration of the solution at a later date but I can't remove it if I want to go back! So I think what I'll do is go with option 2 but keep dosing at 5ml since it's already more than doubling current rates, I can then increase the dose if I see no improvement.


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## a1Matt (13 Jun 2008)

Hi Egmel,

Sorry for gatecrashing your post, but would you mind provinding links to\info on where you bought your Ascorbic Acid and Potassium Sorbate from?

Cheers


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## Egmel (13 Jun 2008)

a1Matt said:
			
		

> Sorry for gatecrashing your post, but would you mind provinding links to\info on where you bought your Ascorbic Acid and Potassium Sorbate from?


No Worries

Ascorbic Acid (Look for the 'pure grade' 100g listing, it should be about Â£4, if it's not there then I'm sure they'll list it if you ask)
Potassium Sorbate
Magnesium Sulphate

Everything else I got form AE


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## JamesC (13 Jun 2008)

Egmel said:
			
		

> ceg4048 said:
> 
> 
> 
> > I can always increase the concentration of the solution at a later date but I can't remove it if I want to go back! So I think what I'll do is go with option 2 but keep dosing at 5ml since it's already more than doubling current rates, I can then increase the dose if I see no improvement.



That's what I'd most likely do as well. Remember though that this formulation is only a match to TPN+ and not a copy as TPN+ uses ammonium nitrate (so I'm led to believe) rather than potassium nitrate. I have used it for several weeks just to make sure it worked, and it did fine but it is quite lean.

All my dosing solutions are made up now as an 'all in one' using ascobic acid and pot sorbate as I find it so easy and haven't had any problems.

Let us know how you you get on with it.

James


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## a1Matt (13 Jun 2008)

Egmel said:
			
		

> a1Matt said:
> 
> 
> 
> ...



Thanks Egmel  I've just dented my paypal account balace a little more


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## Egmel (13 Jun 2008)

JamesC said:
			
		

> That's what I'd most likely do as well. Remember though that this formulation is only a match to TPN+ and not a copy as TPN+ uses ammonium nitrate (so I'm led to believe) rather than potassium nitrate. I have used it for several weeks just to make sure it worked, and it did fine but it is quite lean.
> 
> All my dosing solutions are made up now as an 'all in one' using ascobic acid and pot sorbate as I find it so easy and haven't had any problems.


Well I seem to be getting on ok with the TPN+, I've been using it for a couple of months and have actually reduced my photo-period because everything is growing so fast!

I was going to make up 10l of the solution but I think I'll make less, I'll mix the ascobic acid and pot sorbate in larger quantities separately so I can accurately add them (I don't have the fine scales, only some kitchen ones).  I figured if I added 4g of Ascorbic Acid and 2g of pot sorbate to 100ml of water then I can add 10mls of that per 500ml batch.  That way if I wanted to change the dosing completely I wont have a load of DIY TPN+ hanging about or end up trying to fiddle adding extras, but can start afresh.

What do you currently use?  Your all-in-one listed on your site doesn't look much less lean than the DIY TPN+.  Do you do EI using an all in one solution?

BTW Thank you so much for having worked all this out and sharing it on the web, it's sites like yours that keep the internet a useful place rather than just an interesting distraction 

@ a1Matt, less of a dent than if you'd bought them elsewhere.


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## JamesC (13 Jun 2008)

Currently dosing EI on my main tank to get some new stems grown in quicker and also test how well Utricularia graminifolia grows under EI.

This is my EI solution:

26g Potassium Nitrate
8g Potassium Phosphate
8g Magnesium Sulphate
6g AE Traces
0.5g Ascobic Acid
0.2g Potassium Sorbate
500ml Water

Dosing is 5ml per 40 litres tank water 7 times a week with a weekly 50% water change

Each daily dose gives:

4.0ppm NO3
1.4ppm PO4
3.1ppm K
0.2ppm Mg

PO4 is a little higher than standard EI as I find this works better for me. Also I like to add a little Mg.

My test tank is dosed the high light PMDD+PO4 formulation on my website and yes it is pretty similar to TPN+

Hope that's of help
James


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## Egmel (16 Jun 2008)

Well I made a litre batch over the weekend.

I thought I'd be really clever and make a solution of Ascorbic acid and potassium sorbate to help measure the little quantities... however the limit on how much you can suspend in a solution is quite low   I started off with 20g ascorbic acid and 10g pot sorbate, I was going to mix this with 500ml water then every 10ml would contain enough for a 500ml batch... I've ended up with those quantities in 2l and still it's not fully soluble   Ah well live and learn, it's close enough now that with a good shake I can measure off 40ml per 500ml batch.

The rest went to plan, I didn't use distilled water but instead used filtered then boiled water.  It didn't turn green but more yellow, though I think that was mainly due to the trace elements being a yellow powder.  Nothing settling in it which suggests I've got it right, I'll feed back when I've been using it for a few weeks.


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## a1Matt (16 Jun 2008)

Egmel said:
			
		

> BTW Thank you so much for having worked all this out and sharing it on the web, it's sites like yours that keep the internet a useful place rather than just an interesting distraction





			
				Egmel said:
			
		

> @ a1Matt, less of a dent than if you'd bought them elsewhere.



Very well said on both comments!



			
				Egmel said:
			
		

> Well I made a litre batch over the weekend.
> 
> I thought I'd be really clever and make a solution of Ascorbic acid and potassium sorbate to help measure the little quantities... however the limit on how much you can suspend in a solution is quite low   I started off with 20g ascorbic acid and 10g pot sorbate, I was going to mix this with 500ml water then every 10ml would contain enough for a 500ml batch... I've ended up with those quantities in 2l and still it's not fully soluble   Ah well live and learn, it's close enough now that with a good shake I can measure off 40ml per 500ml batch.
> 
> The rest went to plan, I didn't use distilled water but instead used filtered then boiled water.  It didn't turn green but more yellow, though I think that was mainly due to the trace elements being a yellow powder.  Nothing settling in it which suggests I've got it right, I'll feed back when I've been using it for a few weeks.



This feedback is really helpful for me, I've subscribed to this topic and am eagerly following your progress!


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## JamesC (16 Jun 2008)

Don't worry too much about the amounts of Ascorbic Acid and Potassium Sorbate. I brought myself a nice set of standard measuring spoons off ebay and use the smallest 1/8th teaspoon for the amounts. One 1/8th for the ascorbic and half 1/8 for the pot sorbate dissolved in 500ml solution. Think this weighs a bit more than my quoted amount but it's near enough for my needs. Makes life easy as well which is what I'm after. Can't remember if I mentioned it before but it's best to keep the dosing solution away from light in a cupboard or similar.

Ebay spoons like this are very cheap and handy to use at times - http://cgi.ebay.co.uk/Kitchen-cooks...ryZ20642QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

James


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## Egmel (16 Jun 2008)

Oooh, now there's an easy way   I've got a similar set for dosing things like EasyCarbo but I can't remember what the smallest size is, will have to check when I get home.  

I figured it'd suffer from the same break down as TPN+ so I am indeed keeping it out of the light.

Cheers for all your help.


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