Guillard's F/2 Formula Microalgae Fertilizer Concentrate (8 fl oz (236 ml))

This product really helped my algae take off in growth. I have really dark algae that I feed my corals and copapods.

Keeps the phyto alive, container gets a little sticky but I am on my second bottle

This is my first time buying F/2, so not much to base this on. The instructions say to add 4ml per gallon for 1/2 strength. What? So 8ml per gallon? My reef tank set up is to dose 220 ml of phyto per day. I have two 1 gallon jugs with a air bubbler and LED light strip on each. The dosing pump is in only one of the jars. Once a week, I switch the half full jar with the full one, and then add RODI water at 1.19 salinity to top off the other jug. I then add F/2 to the new batch. I started with only 2ml of this F/2 and it never got to a dark green color. Each week I keep upping the amount of F/2 and am now adding 9ml to each new 1/2 gallon top of to the 1 gallon jug. With the much higher F/2 amounts it is getting a darker green. Perhaps this is due to this F/2 not being very strong. I will try another brand after I use this up and compare.Update: I used the whole bottle and its basically mostly water. I switched to a bottle of Fritz Pro Aquatics and the and my phyto went from a light shade of green tinted water to a very dark, thick solid emerald green overnight. Highly recommend not buying this product and going with Fritz.

Seems to work better than others more expensive. Very happy with the product -it was delivered fast by Amazon, sturdy bottle, and the fertilizer formula is great quality working very well so far with visible results. I believe that while trying to reduce my costs, it is important to trust the products in the fish tank —found both good quality that I can trust at a great price.

This is the first time I’ve ever raised my own phyto, and the first fertilizer I’ve ever used so I have no basis for comparison. But it seems to do the job well. I’ve been yielding a decent volume that is nice and dark green.

The product arrived within 48 hours of my order and was packaged well. We started using the fertilizer and have already noticed positive results. The growth seems faster/stronger than products I've used previously. The phytoplankton is becoming greener by the day. I am very happy with this product and will be ordering again!

Quick delivery and very good pricing. Thank you

Been using this every day for a month the usual time for our 5 gallon cultures and we'll after a month still my light passes through it like there is hardly any potency to it highly wish I went with the one my stepfather is using and won't be buying this for bigger cultures again and will stay with smaller ones if I do