# Lack of magnesium?



## MatPat (Mar 22, 2004)

I recently started using the PPS method of fertilization in my 75g tank. I am using a Hanna pH/TDS/uS meter and Lamotte test kits for all water parameters except for GH (AP test Kit) Here are the water parameters:

Tap:
TDS - 223
pH - 7.4 (rested x 24hrs)
NO3- 0
PO4 - 0
GH - 10
KH - 5
Ca - 44
Mg - 17
CO2 - 7

Aquarium:
TDS - 312 (2 weeks since last WC)
pH - 6.5
NO3 - 13
PO4- 2
GH - 5.5
KH - 5.6
Ca - 44
Mg- 0
CO2 - 56
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gall - 75 g tank, 66g actual

Wpg - 3

Fish load - 24 Rasbora heteromorpha, 3 trios of A. borelli 'Opal', 12 Otocinclus affinis, unknown quantity of Cherry Red Shrimp

Plant mass - Heavily planted, majority is stem plants. Can add the list if needed

Substrate - Eco Complete and Tahitian Moon Sand, 18 months in tank
-
Fertilizer - Just started PPS 4ml SS, 8ml PF, 1ml Mg solution, 1 ml CSM+B Just started PPS yesterday (5/5/05). Prior to that I was adding 1.5 ppm KNO3 daily, 1ppm PO4 every other day and 15ml of CSM+B (2tbsp to 500ml) opposite days of PO4 addition.

For the most part plants have been growing well. When I was using RO/DI water (KH and GH of 3), due to a whole house water softener, Pogostemon stellata 'Broadleaf' was stunted continuously. Since switching back to tap water nearly two months ago (the softened water is not at the kitchen sink) it is now growing better but not great. Nesea pedicellata is doing wonderfully as is Ammania senegalensis/gracilis! I do have the occasional stunting on the regular P. stellata but usually only one stem at a time.

In looking at my tank the TDS is much higher than my tap. I'm guessing this is due to 3x weekly dosing of 15ml of CSM+B (2tbsp in 500ml). 

CO2 levels are high but none of the fish seem stressed. With the Milwaukee controller, I have found that if I set the pH to 6.6, I tend to get green water regularly and the plants do not pearl much. By adjusting the pH on the controller to 6.4 or 6.5 I don't have any problems with green water and the plants pearl much more. I don't use any pH buffers in the tank unless they are in my water supply. Still waiting on the report from the water supplier.

Not really a plant related problem (yet) but it seems that I didn't have any Mg in the water column according to my tests and the PPS spreadsheet. I added 6ppm after the tests. 

Could the stunting of the P. stellata species be caused by the lack of Magnesium in my tank? 

Also, how does magnesium affect the uptake of NO3, PO4 etc, if at all

Thanks!


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## plantbrain (Jan 23, 2004)

I've always associated P stellata stunting with a lack of NO3 in virtually every single case.

It likes higher NO3 levels and at higher light/CO2, those NO3 levels are niot as stable(they decline rapidly).

If you are adding any MgSO4, it's very unlikely Mg is playing a role in stunting.

You would see yellow veining in other plants as well and general lack of green color.

Chlorophyll needs the Mg to appear green.

Regards, 
Tom Barr

3rd annual Plant Fest July 8-14th 2005!
[email protected] Get connected
www.BarrReport.com Get the information


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