[talontsiawd]

I just tore down my 10 gallon to redo it. I plan to rinse the old substrate and add some more (Flourite Black Sand). Is this a good/bad idea? I was planning to put some fert tabs in but since I already have this, I was just wondering as I haven't heard of anyone doing this but can't find any info for or against it at all.

 

[CL]

I've thought about it
If you do it, dont add the iron mixture because it bonds with the other ferts in high concentrations with little water, which would be the case under the substrate (I think)

 

[pandapr]

I was thinking the same thing! About 6 or more on a 75g.

I've heard of people using peat under the substrate. Is this a good idea??

 

[wadesharp]

i heard people using peat in filters but not under the substrate...

 

[Hoppy]

A very thin layer of ground peat under the substrate is beneficial for starting the bacteria that is needed there.

Adding KNO3 or KH2PO4 under the substrate isn't likely to be very effective for very long. Those both dissolve readily into the water, and the NO3 and PO4 ions will easily migrate up into the water column. The K ions may be captured by the high CEC Flourite particles and be more available to the plants. I'm not sure how effective that would be, because I have read that potassium can only be taken up by the leaves, not the roots.