Tom Barr Question

"I am so confused . . . . I thought the general school of thought was to limit phosphorous in order to limit algae. But now you recommend adding phosphorous to take care of green spot algae - why? To what level? "

Plants need PO4 to grow well. I add PO4 to my tanks and do not get algae, folks that 0.0 or 0.2ppm of PO4 have algae, so you tell me if this poppycock works?

My focus has always been on the plant's needs and growth. They are bigger and have higher PO4 requirements per mass than the algae.
This has been old news for about 6 years or so now and a decade with me personally. But that's using CO2.
If you don't add carbon enrichment, then your tank is carbon limited, Trace limited it doesn't matter so much about the PO4. Fish load alone supplies all of that.

The general school of non carbon enriched tank limiting is much more centered around "iron limiting" not PO4 limiting which is much more an old school of thought with CO2 enriched tanks.

"Secondly - my 72 gallon tank is also suffering from spot algae. I have a planted (w/ low light plants) low tech, 1.5 watts per gallon, no CO2 setup. You had noted previously in a different thread here that for this type of setup - you do not add fertilizer to non CO2 tanks except after a water change once every 3 to 6 months. Given this, would you change this to add the PO4 to get rid of the spot algae ?"

No. Apples and oranges. You should not be getting spot algae at all if you have set a non carbon enriched tank up correctly.

"Also, given that I do not use CO2 (and do not have plans to - sorry),"

There's no need to be sorry, I appluad folks that do non carbon enriched tanks.

" would the use of FLourish Excel make sense as a carbon source? From reading, I have seen that many folks had good results with this. Thanks !!!"

Wait a minute. At first you say no carbon and now you do?
Get off the fickle fence. Pick one method and stick with it and do it correctly.

For a non CO2 tank:
Some % odf the surface Floating plants
Deep gravel, eg Flourite/onyx sand 4 inches or so with 1/2 inch of ground peat on the bottom with mulm.
No water changes for many months, only top offs.
Alga eaters, these are more effective per critter since the algae grow slower and there's less light to cause issues.
PACK the tank from the get go with plants.
Have a few plants like Hygro polysperma, Egeria najas, water sprite, moneywort, swords, crypts, java fern, hornwort etc.
These all do well in non CO2 tanks, you will need to play around and see what will do well in the tank till you reach a decent balance.

But in the end, you prune perhaps monthly, clean the glass once every 2-3 months, sometimes less.

But at 1.5 w/gal, adding CO2 makes the tank do the same thing except you can grow most plants, and the plants look nicer. They don't grow super fast since everything is light limited. No algae on the glass either.
Dose once a week and do the usual 50% weekly water change and do one dose after the water change. Don't dose till the next.

You can use the Excel if you want, it'll make the plants grow better. I do not think it'll get rid of the algae but overall the plants will like it. But you've then crossed over into the higher mainteance realm and an added expense which will cost a fair amount on a 72 gallon tank. Excel ain't cheap but it'll make the tank grow better.

Regards,
Tom Barr

Originally posted by plantbrain
".... To what level? "

Plants need PO4 to grow well.

My focus has always been on the plant's needs and growth. They are bigger and have higher PO4 requi/
'rements per mass than the algae.
This has been old news for about 6 years or so now and a decade with me personally. But that's using CO2.
..................
Regards,
Tom Barr

Click to expand...

Old news? To some maybe... I have heard the 'generality' that PO4 is bad too...

In a CO2 enriched tank adding PO4 is pretty routine.

SeaChem even sells a Phosphate product to add to planted tanks to improve growth and also a Nitrogen product that's interesting. Yamato Green is another product made by a different company that adds NO3 and PO4 to tanks etc. They have been selling that for a number of years now. Some of Amano's products likely have PO4.

Both of these nutrients were thought to cause algae and not grow plants but this is not correct and even some more enlighten companies have found this to be true.

The Dutch/German tanks looked so good since the tap water has a fair amount of both NO3 and PO4, all they needed to add was traces with some K+, CO2 and light.

Super- I think in the long run you will be very satisfied with non CO2/carbon enrichment. Plant growth is slower but so is algae. Those floating plants will really help even things out. I shoot for about 10-25% of the surface area coverage. this allows more export of waste into plant tissue if things are overloaded since these plants are not limited by CO2. Also, the roots can get at some substrate CO2 and nutrients since the water column is limited in other nutrients(but not PO4 or NO3 generally).

Regards,
Tom Barr

..so, a 'Ph Down' product that has PO4 in it is not as bad as once thought...for a planted tank that is.. (?) Curious...

pH down, at least the old sttuff is 30% H3PO4, phosphoric acid. You can use this for a source of PO4. It does not effect the pH since you only need a drop or two per 20 gallons to get enough PO4 in the tank.
I used it when I did not have any KH2PO4 for awhile. Fleet enemas are also used often these days: Sodium phosphate. Helps constipated fish also

the relative amount needed to add enough PO4 is very small to the amounts need to effect pH change, add too much Sodium etc.

Some so called acid "buffers" have PO4 based compounds. But folks should only use CO2 gas to manipulate pH in a plant tank, never acid "buffers". If the KH is less than 3 etc, add baking soda but that's about the only buffer one would need to add to a plant tank. There techinically is no acid "buffer". there are buffers and there are acids.

S-
You will need to play around some to get the balance you need. I'd add SAE's, Shrimps etc and remember to feed a little bit to start with and as the plants get better adapted to the tank and grow in more up the feeding, it's your "dosing". It's takes a few months for a tank settle in but it's nice afterwards.

Regards,
Tom Barr