There are only two ways for soluble salts (fertilizers, bio-carbonates, sodium etc) to get out of a container.  Either the plant absorbs them, or they are flushed out with a lot of water. If the water used to flush the container is not either rain water, or distilled water, it too could be adding additional soluble salts with each watering.  If the  small tree's root system does not fill the complete volume of the container, these soluble salts quickly begin to accumulate causing many problems for the tree.  If the medium is frequently flushed to remove the harmful ingredients, the unused portion of the medium is constantly water longed and compacted.

It was common thought that it was beneficial to line rocks  or other chunky ingredients along the bottom of a container to promote drainage.  However, it is now known that doing so is not a good idea, as it simply raises the perched water higher into the container, leaving less room for root growth.  A growth medium for a citrus tree, MUST provide good drainage, and good air porosity. Most mediums made from straight bagged potting soils meet these requirements ONLY for a short period of time, then problems will quickly begin. Dr. Carl E. Whitcomb, Ph.D  in his book "Plant Production In Containers-11" recommends a 3-1-1 mix made from 3 parts 1/4"pine bark (or other conifer barks), plus 1 part good Canadian peat, plus 1 part concrete sand.  I've used this mix with citrus and it works well.  Other growers I know use what is called a 5-1-1 medium, which consists of 5 parts small bark, 1 part peat moss, and 1 part perlite.  This medium also is reported to work well, but requires very frequent watering, and has a very fast water pass through (which might not work well in your Mother-In-Laws living room rug.   

Is this the tree we are talking about?
https://www.amazon.com/Red-Lime-Tree-Bearing-Branched/dp/B074W9TTNN/ref=sr_1_4?ie=UTF8&qid=1509732000&sr=8-4&keywords=red+lime+tree

Recently I've been reading advice that when a container tree has a couple inches of the root ball cut and then the tree being put back into the same container, that trimming back the foliage is not necessary.  Also when I fertilize a tree I dissolve the fertilizer  and pure it over the entire surface of the root ball, so that the entire root ball is evenly whetted..

Orange production in Brazil’s citrus belt is forecast to drop by almost a third during the 2018-19 season, according to an industry association. The decline is attributed to disease, mainly citrus canker and citrus greening (HLB). The number of properties producing oranges over the last few years has shrunk by 20%. Sao Paolo Agriculture Secretary Francisco Jardin said that although the state’s orange industry remains one of the largest in the world, the high number of abandoned groves was a concern.

Non Poncirus cultivars have straighter thorn, flying dragon cultivars have strongly curved thorns.  Further the trunk and branches of FD will have a pronounced zig-zagged growth.

Over the years I have started numerous trees from seed.  Out of all of these seed grown trees, only one tree, a Saint Dominic Sour orange tree ever grew for a long enough time, and grow high enough to fruit. It is planted in a bottomless Root Maker expandable container. The roots have grown into the ground.  This tree now produces a good amount of fruit.

Note that Flying Dragon (FD) seed do not produce the true FD cultivar 100% of the time.  Only about 50 percent +- will be the true cultivar.   

Because Forumfool is in California, he can only  purchase from an in state supplier.  No out of state nursery will ship a citrus tree to California.

I have an in ground seedless Marsh grapefruit tree.  I picked a few fruit in late February, the taste was OK (my wife said it was too sour).  I picked some fruit about March 20.  The taste was better.  I personally liked the taste, my wife said it was too sour.  I picked the last fruit April 15.  On April 15, I noticed the fruit had begun to become soft, the taste was excellent.  My wife said that the fruit was much better,  NOTE: she is a sweeter red grapefruit fan, and I am a white grapefruit fan.  Were still very good friends.

I have many times set my Root Maker and other containers in a larger bucket over night. to soak, with or without fertilizer..

 Generally insoluble dietary fibers are acquired by utilizing citrus peel owing to the occurrence of bioactive components, and other different nutrients. It has abundant nutritional benefits as well as functional properties. They are also known to have significant health advantages for instance fat metabolism, improved digestion, and prevent breast and gastric cancers. Citrus fibers have a range of advantages and they act as a prospective anti-allergen; therefore, the market is gaining demand and popularity globally. The rising demand for natural dietary fibers for avoiding different diseases is the major aspect fueling the demand and popularity of citrus fiber market. With the growing population, the demand for dietary fiber and improving the standard of living is anticipated to aid the market growth within the forecast period

z-willis you should not have washed off the white residue, doing so took away urea's advantage..   The white residue was urea.  A plant's leaf can only absorb nutrients applied as a foliar spray as long as the spray remains wet on the leaf. Urea has a big advantage over other nitrogen sources in that urea is VERY hydrophobic.  When the humidity rises the dried urea foliar solution will re-hydrate and the tree once again absorbs more nutrition. No other nitrogen fertilizer has that ability.