Consequences of over-dosing MgSO4?

AndyTaylor

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1 Jul 2008
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I can't find a smiley that conveys *smacks self really hard on head* so here goes......

I've just realised that the MgSO4 solution that I've been dosing for 3 weeks was 6 times stronger than I had thought it was.

I've been dosing to 30ppm every second day instead of my aimed-for 5ppm. As per my earlier thread I've also been fighting a losing battle with BBA, GSA, and (I think) Staghorn.

Would anyone care to advise me if there is a connection between my mis-calculation and my algae crop?
 

ceg4048

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NO.

BBA=Poor CO2/flow
GSA=Poor CO2 and/or Poor PO4/flow
Staghorn=Poor CO2 and/or overfeeding, however since BBA is present suspect poor CO2

6X MgSO4 dosage=High TDS and poor economics (i.e. waste of money)

Cheers,
 

tanker

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Does MgSO4 makes the water harder?
i'm asking this because i have tonina, and since i dosed some MgSO4, it look pretty bad. could also because of other problems as well, but i am trying to eliminate possible cause. i just trimmed and replant the top part and its stopped growing. it was growing fine before i trimmed it and started MgSO4, i've since stopped MgSO4.
 

AndyTaylor

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ceg4048 said:
NO.

BBA=Poor CO2/flow
GSA=Poor CO2 and/or Poor PO4/flow
Staghorn=Poor CO2 and/or overfeeding, however since BBA is present suspect poor CO2

6X MgSO4 dosage=High TDS and poor economics (i.e. waste of money)

Cheers,

Thanks ceg4048. Succint as always! :)
 

san-ho-zay

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Otley, UK
tanker said:
Does MgSO4 makes the water harder?
Yes. It contributes to general hardness (GH) but using it alone would not be a balanced way to increase GH. If you look at AE's GH booster, you'll see it adds Calcium, Magnesium, Potassium and Iron. MgSO4 is used specifically to boost Magnesium.

MgSO4 doesn't affect carbonate hardness (KH).
 

ceg4048

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tanker said:
Does MgSO4 makes the water harder?
i'm asking this because i have tonina, and since i dosed some MgSO4, it look pretty bad. could also because of other problems as well, but i am trying to eliminate possible cause. i just trimmed and replant the top part and its stopped growing. it was growing fine before i trimmed it and started MgSO4, i've since stopped MgSO4.

Hi tanker,
Yes, adding Mg increases the GH. Tonina is sensitive to KH but it wouldn't surprise me if high TDS or GH was also a problem. I've grown it in medium high KH + high GH water but the margin of error was always very narrow. Barr advises optimal ranges of KH 2-3 and for GH, not much more than about 7. My standard operating procedure (SOP) is to add more CO2 but to avoid Excel for this species.

There are a handful of plants optimized for soft water and this short list includes Tonina, however, it seems to me that most of them are also very inefficient CO2 feeders as well so you normally need to have good CO2/flow.

Cheers,
 

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