Fighting Algae with Borax

[aylad]

When attached to the algae cells, the large molecule tends to block the ion channels preventing the cells from getting nutrients (positive charged ions, including phosphates, nitrates and carbonates) from the water. Richard

Seems to be one more reason to avoid the phosphate removers?

Janet

[waterbear]

Seems to be one more reason to avoid the phosphate removers?

Janet

Not really since phosphate removers remove phosphates and eliminate ONE of the sources of algae nutrition. There are still carbonates and possibly nitrates in the water that the algae can feed on. THAT is the reason that phosphate removers are not really necessary.

[chem geek]

I may be wrong about this, but I believe that nitrogen and phosphorous are both required nutrients -- it's not an "or" relationship. This link describes some of the nutrient requirements and this link talks more about the N:P ratio and how a lower ratio can lead to algal blooms and this link refers to N-limited vs. P-limited algal growth with the strong implication that both nutrients are required (i.e. both nitrates and orthophosphates). I've read other info that's consistent with this. I think the only either/or situation was between phosphorous and silicon for some species of algae that could or do use silicon instead of phosphorous. You'll also find C:N:P ratio data that adds carbonates to the mix, but again it's not an "or" relationship but an "and" relationship (i.e. all are required nutrients so eliminating any of them will eliminate algal growth).

We can't obviously eliminate carbonates from the water since it's exposed to carbon dioxide in the air and we want a pH buffer and calcium carbonate saturation. Ammonia may be present as a source of nitrogen, but only if chlorine is not present (since monochloramine occurs very, very quickly), but monochloramine would be taken up as algae food and would then kill the algae. So realistically it is nitrates that would be a source of nitrogen for algae. Typically the nitrates and phosphorous would both get into pools from fertilizer (i.e. blown soil), but nitrates can also come from the oxidation of organics (where nitrates are produced instead of nitrogen gas) and nitrogen gas itself can combine with oxygen and water to form nitrates (this is actually slightly thermodynamically favored and were it not for living organisms doing denitrification, biosynthesis and nitrogen fixation, the oceans would be 0.1 Molar HNO3).

Richard

[heymom1]

When you add the borax and muriatic acid, is it a one-time application? Or do you have to keep going back and fiddling with it? We've gotten rid of our mustard algae (but it rained again today) with high CL levels consistently, and now it's either time to start adding Polyquat or go the Borax way. I need easy. I will tell you that I don't like dealing with muriatic acid, I just don't - chemicals that smoke as you open them scare me. So if the borax is a one-time application (per season) I can go that way, or do the Polyquat.

Recommendations?

[chem geek]

The Borax + Acid is one-time except for small additions to compensate for dilution (splash-out, backwashing, rain overflow, etc.).

[waterbear]

If you initially add 50 ppm just monitor it and when it drops to 30 ppm bump it back up to 50 ppm.