Lessions learned on Alage and Phosphates

[Cermet]

For plants to work and algae to fail one must be very careful about nutrients in the water - these are needed to feed the plants, but these vital substances must remain in balance and must be removed if levels start to accumulate above desirable values. There are many ways to achieve these objectives but there are far more ways for the balance to fail and then algae to grow.

Unless you have very dense plants (which also means high light/CO2 injection) than you will almost always have high phosphates. This most often has to do with feeding fish in a closed system like a tank and the fact that the tank water does not turn over numerous times per day with fresh water like streams do in nature.

So, first off, I suggest a phosphate test kit (Seachem.) Such a kit gives you a handle on this troublesome nutrient. That, along with a nitrate test kit will help you keep your plants properly fed without incorrect levels of these nutrients occuring, which can often lead to algae growth.

If phosphates get high (anything approaching 1 ppm is getting there in a low density, low light system) than water changes are either not big enough and/or often enough.

If water changes are an issue for any reason (cost/difficulty) and/or large WC's cause nitrates to keep getting too low (bad for plants yet very good for algae growth), consider a small, in tank algae scrubber - mine has dropped my normally 2-3 ppm phosphate level (even with water changes of over 50% twice a week) down to the 0.05 ppm level. I also tried phosphate absorbers but that was $$$ and doing the weekly testing of phosphates levels to determine absorber replacement times was both a bother and ran through test kits rather fast.

Of course, one must feed nitrate if these levels drop below 2-3 ppm in the tank due to a scrubber (not an issue with absorbers) but that is rather easy, and low cost.

Avoid all solid or liquid fertilizers with phosphate since fish will provide more than enough even with a scrubber or absorber (unless you decide not to keep fish.)

This issue has been a battle for me for some time and only recently have I learned these solutions - the hard way.

[jeffs99dime]

I just want to add that excess silicates are also an algae promoter.

[Lady Hobbs]

Phosphates, for me, are 2 right out of the tap. I believe phoshpates should be around .25-.50 for planted tanks. And of course food contains phosphates, as well.

[Taurus]

If water changes are an issue for any reason (cost/difficulty) and/or large WC's cause nitrates to keep getting too low (bad for plants yet very good for algae growth), consider a small, in tank algae scrubber - mine has dropped my normally 2-3 ppm phosphate level (even with water changes of over 50% twice a week) down to the 0.05 ppm level.

Cermet-

This is a very informative post. Could you please provid a link to an illustration of the in tank algae scrubber.

I found a Wikipedia entry on an algae scrubber here:

http://en.wikipedia.org/wiki/Algae_scrubber

How is the in tank design different?

Thanks

[Taurus]

I just want to add that excess silicates are also an algae promoter.

Excess silicates promote diatoms. I didn't realize excess silicates promoted algae as well?

[dmagerl]

Do you have a link explaining what an algae scrubber is and how to set one up?

[Cliff]

Do you have a link explaining what an algae scrubber is and how to set one up?

Here's one that I used. I have also found people with Fresh water set-ups using the same set-up as the ones typically found in marine aquariums

http://algaescrubber.net/forums/show...cs-The-Summary

[jeffs99dime]

Excess silicates promote diatoms. I didn't realize excess silicates promoted algae as well?

Diatoms are brown algae.

[Cermet]

I will get a picture of an in tank algae scrubber soon - it is just two microwave plates with magnets. The complete unit is very small and can be easily hidden in a tank (even a small tank.) The outside plate (in the air) has red LED's and the underwater unit has a short section of air hose with holes and a standard roughen screen glue inside. This very small unit keeps a 75 gal very low in nitrates and phosphates. A commercial version (either as parts or completed or just a free license to build one) is available and searching past posts should turn it up.

[Cermet]

Phosphates, for me, are 2 right out of the tap.

Ugh! and to think I complained about my tap water nitrates being 10 ppm (my phosphates from the tap are undetectable so below 0.01 ppm)! Your phosphate readings are rather high; for plants, your lower number range sounds right on.